Since Classical times up through the violence of World War I, the issue of control of the Bosporus, Sea of Marmara and Dardanelles—the Turkish Straits, which connect the Black Sea with the eastern Mediterranean—has vexed kings and admirals and led to the rise and fall of empires. When the largest global conflict until that time ended in November 1918, the newly emerged Republic of Turkey, led by Mustafa Kemal Atatürk, was committed to restoring its sovereignty over the Straits while providing for the commercial and naval concerns of Black Sea and non–Black Sea countries in an equitable manner. With Communism, Fascism and Nazism beginning to roil the European continent, Atatürk’s diplomatic abilities to compromise resulted in the 1936 Montreux Convention regarding the Regime of the Straits. Thanks to its shrewdly written text, that 86-year-old treaty remains relevant and in force in the 21st century, despite periodic diplomatic complaints about the document by both signatory and non-signatory countries.
Calls to annul or revise the Montreux Convention have come up again and again in history from various quarters, including the United States, which sees the treaty as offering lopsided benefits to the Russian navy. Likewise, the North Atlantic Treaty Organization (NATO) has chafed at the restrictions to non-littoral Alliance vessels wishing to operate in the theater, particularly during crisis situations. Nevertheless there has been no NATO naval presence in the Black Sea, beyond the navies of the littoral Alliance members, since December 2021, even before Ankara declared it would block the Straits due to a state of war in the region. At the same time Turkish President Recep Tayyip Erdoğan’s long-running plans to build a new canal across Istanbul have raised concerns in certain quarters that the Montreux Convention might soon be dropped or rewritten.
During peace time, the Turkish Straits are mostly open to all civilian shipping, with certain restrictions in particular on naval vessels from non–Black Sea littoral countries—including maximum tonnage and time allowed to stay in the basin. Whereas, three articles specifically modify the peacetime rules safeguarding warships’ rights to transit during times of war: Articles 19, 20 and 21. These permit Ankara to refuse passage for naval vessels of belligerent countries (with a return to home port exception—Article 19) or effectively any ships at all if Turkey is a party to the war or feels imminently threatened (Articles 20, 21, respectively).
Montreux’s continued relevance was reaffirmed after Russia launched its massive re-invasion of Ukraine on February 24, 2022; days later, Ankara invoked Article 19, closing the Straits to both regional warring states’ navies but also declared the passage closed to all non-littoral powers. This closure has had the most profound operational implications for the Russian naval forces participating in the war, marooning a portion of its fleet in the Eastern Mediterranean and preventing Moscow from replacing the losses it has suffered in the Black Sea basin. In the current conflict, Montreux, as designed, plays its dual roles as both referee and goalkeeper.
On February 24, 2022, in an early-morning televised address at 05:55 Moscow time, Russian President Vladimir Putin announced a “special military operation” to “demilitarize” and “denazify” Ukraine, which began minutes later. The massive assault caught Western politicians by surprise and immediately raised questions about how the North Atlantic Treaty Organization (NATO) might assist Ukraine, even though the latter is not yet a member of the 30-country alliance. It was almost immediately realized that navigation issues pertaining to the Black Sea basin—on the one hand, freedom of access to this body of water for Ukraine’s Euro-Atlantic partners, and on the other hand, blocking the Russian navy’s comings and goings—would be a crucial pillar of this Western support to Kyiv.
The sole maritime passage between the Black Sea and the Mediterranean is collectively known as the Turkish Straits, a 164-nautical-mile-long channel consisting of the Bosporus and Dardanelles straits and the inland Sea of Marmara, which lies between them. NATO member Turkey exercises total sovereignty over the Straits, but its ability to regulate maritime traffic across them is conscribed and defined by the 1936 Montreux Convention Regarding the Regime of the Straits, frequently referred to simply as the Montreux Convention. The Montreux Convention’s articles clearly differentiate between commercial shipping and warships; in peace time, the former are allowed unhindered free passage, while the latter are subjected to numerous restrictions, including whether the naval vessels belong to Black Sea riparian countries or are foreign. The Montreux Convention is weighted heavily in favor of the fleets of Black Sea riparian nations.
In the new regional maritime environment of the Russian-Ukrainian conflict, earlier calls for reconsideration and possible modification of the 86-year-old treaty, including surprisingly from some Turkish politicians, have reemerged. Yet more immediately, days after Russia began its “special military operation” against Ukraine, the Turkish government chose to exercise its treaty right to unilaterally close the Straits to naval traffic. And that decision has had critical implications for the further course of the war.
A Brief History of Conflict in and Around the Turkish Straits
The Eastern Mediterranean and the Turkish Straits have been fought over for millennia, with the Montreux Convention representing an early-20th century diplomatic effort to constrain such conflicts. One of Europe’s first great literary works, The Iliad, written down around the 8th century BCE and credited to the Greek oral poet Homer, tells how King Agamemnon of Mycenae led an alliance of Greek city-states to undertake a decade-long siege of Troy, a prosperous walled city situated in Asia Minor at the entrance to the Dardanelles. Long thought to be fiction, an artificial mound at Hisarlık, now roughly 4 miles (6.5 kilometers) equidistant from the Aegean and the Dardanelles, which was first excavated in the mid-19th century by amateur archeologist Heinrich Schliemann, has been put forward as the historical site of Troy. Though debate on this topic continues to rage on in the academic literature.
Three centuries after the chronicling of The Illiad, in 492 BC, Persian king Darius the Great launched his empire’s first invasion of Greece, intended to punish the city-states of Athens and Eretria for supporting Ionian cities against Persian rule. The Greek historian Herodotus in his Histories recounts how Darius’ military engineers constructed a half-mile floating bridge across the Bosporus to permit his troops to cross from Anatolia into Thrace to begin their march on Greece. Herodotus subsequently notes that in 480 BC, Darius’ son Xerxes I prepared for the second Persian invasion of Greece by ordering two pontoon bridges built across the Hellespont (Dardanelles) to allow his army similar passage.
Two millennia later, control of both the Dardanelles and Bosporus would prove crucial in the Ottoman campaigns, first to capture Constantinople and subsequently to invade Eastern Europe and the Balkans. In the mid-14th century, during the civil war over Byzantine succession, claimant John Kantakouzenos (later Byzantine Emperor John VI) concluded an agreement with Ottoman Beylik ruler Orhan Ghazi for military support. Orhan subsequently crossed the Dardanelles and ravaged Thrace, permanently establishing an Ottoman military presence in Europe, despite Emperor John VI’s subsequent requests that he to withdraw.
On May 29, 1453, troops of Ottoman Sultan Mehmet II, subsequently known Fatih (“the Conqueror”), stormed and captured Constantinople, extinguishing the Byzantine Empire and establishing a permanent Turkish presence in Europe. Prior to besieging Constantinople’s land walls, Mehmet had his engineers construct fortifications at Rumeli Hisarı, just north of the great city on the western shore of the Bosporus Strait.
The Rumeli Hisar fort was deliberately built next to the Strait’s narrowest point, only 2,170 feet (660 meters) across. Also known in Turkish as Boğazkesen (“cut-throat,”), the epithet emphasized the military structure’s tactical importance for closing the channel, as its enfilading artillery’s field of fire interlinked with its opposite, Anadolu Hisarı. The latter, eastern fort was built in 1393–1394 by Ottoman Sultan Bayezit I, in preparation for his own, failed siege on Constantinople; it is the oldest surviving Turkish architectural structure built in Istanbul on the Bosporus’ Anatolian coast.
In 1453, the two completed fortifications’ interlocking artillery fire effectively closed the channel to incoming assistance for Constantinople from Genoa’s Black Sea colonies. Mehmet’s victory reverberated throughout Christendom and began a period of Ottoman domination of the Turkish Straits that would survive until the end of World War I and the fall of the Ottoman Empire. Two decades after the Ottoman capture of Constantinople, in 1477, Gedik Ahmet Pasha conquered the Crimean Peninsula, which would effectively turn the Black Sea into an Ottoman lake for more than two centuries, until Russia became strong enough to contest Turkish suzerainty there.
Even prior to building Rumeli Hisarı, Sultan Mehmet further sought to tighten Ottoman nautical control of the Straits and isolate Constantinople by constructing the Kilidülbahir fort on the European shore of the Dardanelles in 1452. But this stronghold’s Anatolian counterpart, Seddulbahir, was only erected two centuries later, in 1659, in response to the rival Venetians occupying the Eastern Mediterranean islands of Lemnos and Tenedos, at the entrance to the Dardanelles, three years earlier.
In 1695, geopolitical concerns led Russian Tsar Peter I (later given the epithet “the Great”) to attack the Ottoman fortress at Azov, on the Don River, which flowed into the Sea of Azov, the northeastern appanage of the Black Sea. While the assault failed, the tsar returned the following year with a hastily constructed galley fleet; the date is commemorated as the beginning of the Russian navy. Even though the 1696 assault captured Azov, the Russians had to return it in the subsequent peace settlement. The Azov campaign represented the first of the Russian Empire’s eventual 11 conflicts with the Ottoman Empire, which ended only when World War I destroyed them both.
It fell to Peter’s successor, Empress Catherine II (also later called “the Great”), to make Russia a Black Sea power. Her victories during her war with the Ottomans, 1768–1774, allowed Russia to gain access to the Black Sea by annexing what is now southern Ukraine, where her government founded Odesa, Mikolaiv and Kherson. Centuries later, these settlements became key front-line cities in the Kremlin’s 2022 attack on Ukraine.
Catherine II’s war against the Ottoman Empire ended with the 1774 Treaty of Küçük Kaynarca, whose favorable terms for Russia included territory encompassing Azov, Kerch, Yenikale, Kinburn and the Black Sea coast delineated between the Dnieper and Bug rivers. The Russian victory also ended restrictions on its naval and merchant shipping in the Sea of Azov, granted Russia the right to petition on behalf of Orthodox Christians under Ottoman rule, and, lastly, made the Crimea Peninsula a Russian protectorate. Tsarina Catherine dropped all pretense, however, and annexed Crimea nine years later, the same year in which the future Black Sea Fleet base of Sevastopol was founded in the finest deep-water port on the Black Sea.
Russian influence over the Ottoman Empire would reach its zenith with the bilateral Treaty of Hünkâr İskelesi. Signed on July 8, 1833, the document rewarded Russia for having dispatched its Black Sea Fleet and troops to defend Constantinople from an Egyptian army threatening to overthrow the Ottoman Empire. When government officials questioned the Sultan as to why he accepted assistance from his Empire’s traditional enemy, Mahmud II reportedly replied, “A drowning man will clutch at a serpent.” Under the terms of the treaty, valid for eight years, both the Bosporus and Dardanelles could be closed to foreign warships if Russia requested it. Superseded by the July 1841 London Straits Convention, signed by Russia, the United Kingdom, France, Austria and Prussia, the new treaty reaffirmed the “ancient rule” of the Ottoman Empire by closing the Turkish Straits to all for warships during wartime except those of the Ottoman sultan’s allies. Efforts around that time by Tsar Nicholas I to achieve a European consensus over the “Eastern Question”—what to do if the Ottoman Empire, the “sick man of Europe,” declined further—were rebuffed.
The new diplomatic pact failed to dispel the cloud of suspicion surrounding the aforementioned 1833 Hünkâr İskelesi agreement when the Crimean War erupted in October 1853, after the Ottoman Empire declared war on Russia. Five months earlier, in May, with armed conflict seemingly inevitable, Russia’s Black Sea Fleet commander, Admiral Vladimir Kornilov, had drawn up a “Cruising program between the Bosporus and Sevastopol” and advocated for a preemptive strike on the Bosporus. In the wake of Russia’s November 1853 naval victory at Sinop, on Turkey’s Black Sea coast, the British and the French fleets entered the Black Sea in January 1854 to forestall a seemingly likely Ottoman collapse. By September, the Anglo-French fleet landed troops in Crimea to besiege Sevastopol and destroy the Black Sea Fleet. Kornilov had vociferously argued for sending the Black Sea Fleet to attack the Anglo-French at sea but was overruled by his superior, Prince Alexander Menshikov, who called for scuttling Russian naval force in Sevastopol to defend the harbor. The Western European powers’ siege of Sevastopol lasted 349 days, until the city’s capture shortly before the war ended in March 1856, with the Treaty of Paris.
The victors imposed a harsh peace upon the Russians; the treaty proclaimed the Black Sea as neutral, closing it to all warships and prohibiting coastal fortifications, which effectively neutralized Russia’s Black Sea naval efforts since the time of Peter the Great. With Russia forbidden to have a naval presence in the Black Sea basin, the treaty thus nullified the strategic importance of Sevastopol as a naval port. Russia would chafe under the terms of the treaty until France’s defeat in the 1870–1871 Franco-Prussian War, when diplomatic support from the new German Empire, combined with a more moderate diplomatic approach by a humbled France, allowed Russia to denounce the Treaty of Paris restrictions and begin to rebuild its Black Sea naval presence.
Naval events in the Straits at the outset of World War I were instrumental in persuading the initially neutral Ottoman Empire to join the German and Austro-Hungarian side. On August 3, 1914, after war was declared, the German Kaiserliche Marine Mediterranean Division’s Moltke-class battlecruiser SMS Goeben and Magdeburg-class light cruiser SMS Breslau, then at the Austrian Navy’s Adriatic Pola base, dropped plans to return to Germany and instead set sail for Constantinople; the decision followed secret German negotiations with Ottoman War Minister Enver Paşa. After the elderly and outgunned British 1st Cruiser Squadron declined to engage the German pair, they arrived at the Dardanelles on August 10. As the Ottoman Empire was still officially neutral, to circumvent neutrality regulations, the German government generously offered to “gift” the ships into the Ottoman Navy. On August 16, renamed Yavuz Sultan Selim, SMS Goeben became the flagship of the Ottoman Navy and SMS Breslau became Midilli.
Swapping out their German uniforms for Ottoman ones and fezes, in November, the two ships’ crews led a squadron across the Black Sea to bombard the Russian fleet and Russian Black Sea ports, resulting in British and Russian declarations of war on the Ottoman Empire.
The next year opened with a disastrous British naval campaign designed to knock the Ottoman Empire out of the war, hinging on the Royal Navy forcing the Dardanelles and capturing Constantinople. On March 18, 1915, a combined Anglo-French squadron entered the Dardanelles, only to retreat due to heavy artillery fire and mines, which sank three battleships and heavily damaged three more. Even though the incursion alerted the Ottoman government to Allied intentions, the United Kingdom two months later launched the ill-fated Gallipoli campaign, nearly within sight of the fabled ruins of Troy. By the time the British withdrew after eight months, the bloody land campaign had claimed over a third of a million men, either killed or wounded.
When the Armistice ended World War I in November 1918, four European empires had been destroyed: the Austro-Hungarian, German, Ottoman and Russian, with hastily assembled new nation-states arising from the rubble. The Paris Peace Conference produced both the 1919 Treaty of Versailles and the 1920 League of Nations, followed by the 1922 Washington Naval Treaty, all intended to produce a more just postwar world and diminish the chances for yet another global conflagration. Complicating these laudable intentions, the next two decades would see the rise of fascism in Italy and Germany and a redrawn map of the Middle East, with the UK and France establishing protectorates there even as a new Republic of Turkey was forged in a nationalist war to repel foreign occupiers.
Antecedents of the Montreux Convention: The Sèvres and Lausanne Treaties
After World War I, international concerns over the Turkish Straits entwined with Turkish nationalists fighting a foreign occupation. The Ottoman Empire began to fracture, assisted by the victorious Allies’ plans for partitioning the “sick man of Europe.” In August 1920, Ottoman government official signed the Treaty of Sèvres, which not only created occupation zones in the Empire but also directly ceded significant territories to the UK, France, Italy and Greece. The treaty also established a Zone of the Straits, under the control of the League of Nations’ International Straits Commission, which would internationalize the Bosporus, Sea of Marmara and Dardanelles by permitting full navigation to warships and merchantmen of all countries in both peace- and wartime.
The Treaty of Sèvres not surprisingly outraged Turkish public opinion and ignited Turkish nationalists against both the decrepit Ottoman government and the foreign occupiers arriving under the treaty terms. A hero from the Gallipoli campaign, Mustafa Kemal Atatürk, led Turkish nationalists to defeat the Ottoman reactionaries and the foreign invaders during what came to be known as the Turkish War of Independence. Three years later, the 1923 Treaty of Lausanne modified or removed the most noxious terms of the Treaty of Sèvres. It created the internationally recognized sovereign Republic of Turkey upon most of the Ottoman Empire’s Anatolian territory populated by ethnic Turks, as well as restored the Straits to Turkish control under the condition that Turkey keep them demilitarized and allow all foreign warships and commercial shipping free passage.
The last condition angered Turkish patriots, and the new nationalist Turkish government under President Atatürk, in developing a national security strategy, eventually rejected the noxious terms of the Treaty of Lausanne. Turkey subsequently remilitarized the Straits area over the following decade, much as the Russians in the previous century had repudiated the more onerous terms of 1856 Treaty of Paris, which had ended the Crimean War by abolishing Russian sea power in the Black Sea.
The Montreux Convention Regarding the Regime of the Turkish Straits
After protracted diplomatic negotiations between the World War I victors and the vanquished, full Turkish sovereignty over the Straits was formalized in the July 20, 1936, Montreux Convention Regarding the Regime of the Turkish Straits. The conference was attended by the Union of Soviet Socialist Republics (USSR), Turkey, the United Kingdom, France, Bulgaria, Romania, Greece, Yugoslavia, Australia and Japan. The conference was convened at the suggestion of Turkey to revise the Convention on the Black Sea Straits, approved by the 1922–1923 Lausanne Conference. The United States was also invited to the conference that preceded the signing of the Convention but declined to participate and, consequently, was not a signatory.
Three important positions needed to be balanced: the competing agendas of Turkey, the Soviet Union and the UK. Turkey, as the country with the longest Black Sea coastline, wanted to remilitarize the area and gain as much control over the Straits as possible; the USSR wanted unrestricted passage so that its Black Sea Fleet could access the Mediterranean; while the UK, ever concerned about the Suez Canal, its lifeline to India, in turn wanted some limitations placed on potential Soviet influence in the Mediterranean. Not surprisingly, the accord ended up being a compromise between the three positions. The Soviet Union and a number of other states had not been able to agree to the terms of the Lausanne Conference and not only never ratified it, but continued to fight against it. For the opponents of the Lausanne Conference, the best element of the Montreux Convention was that it terminated the detested International Straits Commission, imposed by the Treaty of Sèvres.
Briefly put, Montreux, signed by the UK, Bulgaria, France, Greece, Japan, Romania, Turkey, the USSR and Yugoslavia, placed the Straits under sovereign Turkish control. The Convention treats the Straits as an international shipping lane, completely open to commercial vessels, all the while delineating the rights of Black Sea riparian countries and their naval forces but allowing Turkey the right to restrict the naval traffic of non-Black Sea states.
The Convention contains 29 articles, 4 annexes and 1 protocol. While Articles 2–7 cover the passage of merchant ships transiting the Turkish Straits, over half of the Conventions Articles 8–22, concern the passage of warships, separating them into Black Sea riparian and foreign vessels, giving the former significant rights and privileges. In peacetime, the Convention broadly guarantees the general right of warships of all countries to transit the Straits but with a bias toward the Black Sea riparian states of Turkey, Bulgaria, Romania and the Soviet Union. Foreign warships seeking passage may not have a displacement greater than 15,000 tons and may not remain in the Black Sea longer than 21 days, whereas Black Sea navies are exempt from those restrictions.
Three articles specifically modify the peacetime rules safeguarding warships’ rights to transit during times of war: Articles 19, 20 and 21, all of which have garnered much attention since Putin began his assault on Ukraine.
Article 19 specifically regulates the passage of warships of belligerent powers through the Bosporus, Sea of Marmara and Dardanelles straits when Turkey is not a party to the war. Article 19 states that, at such times, “warships [not belonging to any of the respective warring parties] shall enjoy complete freedom of transit and navigation through the Straits” under the normal peacetime rules. However, the warships of belligerent states “shall not […] pass through the Straits” except if a) one of the belligerents is acting under lawful collective defense rights obligations that Turkey is also a party to or b) any belligerent warship must pass through the Straits to return to its base.
During the present Russo-Ukrainian conflict then, Russian Black Sea Fleet warships currently deployed outside the Black Sea could return northward through the Straits while Russian non-Black Sea Fleet warships currently operating in the Black Sea, such as the Baltic and Northern Fleet amphibious landing ships that arrived in early February 2022, could depart. However, no further transfers of Russian warships through the Straits would subsequently be permitted until the end of hostilities.
Article 20 applies when Turkey itself is involved in the conflict. In such cases Turkey has complete discretion over all warship navigation through the Straits, and no state, whether Black Sea or non–Black Sea, then enjoys freedom of transit or navigation through the Straits without the Turkish government’s express approval.
Article 21 applies a constrained interpretation of Turkey’s Article 20 powers when Turkey “considers itself to be threatened with imminent danger of war.” As with Article 20, such a circumstance would suspend operational peacetime regulations on warship passage. Unlike Article 20, Article 21 stipulates that warships separated from their bases by the Straits must generally be allowed to transit to return home. Furthermore, if Turkey invokes Article 21, it must notify other High Contracting Parties. As originally written in the 1936 text, if two-thirds of the “Council of the League of Nations” and half of the High Contracting Parties reject Turkey’s measures as unjustified, Turkey’s Article 21 invocation is suspended.
Finally, under Article 24 of the Montreux Convention, Turkey is required to supervise “the execution of all the provisions […] relating to the passage of vessels of war through the Straits.”
Unlike in World War I, which it entered at the conflict’s outset, Turkey remained neutral in World War II, until declaring war on February 23, 1945. It had strictly interpreted the Montreux Convention as affecting Nazi German warships, thus largely preserving the Black Sea as a low-grade theater of operations during the life-and-death struggle. Following its declaration of war on Germany, Turkey for the first time invoked the Montreux Convention’s Articles 5 and 20 and declared a “state of war,” thus allowing it to ban German and Italian warships from using the Turkish Straits to gain access the Black Sea. Despite this, the USSR in March 1945 denounced the 1925 Soviet-Turkish Treaty of Friendship and Neutrality, believing that Turkey had violated the Montreux Convention in May-June 1944 by surreptitiously allowing 13 Kriegsmarine auxiliary warships through the Straits under the guise of civilian ships after their armaments were partially removed before the passage and returned after it.
In June–July 1945, following the Allied victory over Germany, the always opportunistic Joseph Stalin had Soviet Foreign Minister Viacheslav Molotov give the Turkish ambassador Selim Sarper a list of conditions he expected to be fulfilled. These included joint Turkish-Soviet control over the Straits, the provision of military bases in the Bosporus and Dardanelles to the Soviets, and the return of Kars and Ardahan districts to the USSR.
Stalin also raised the question of the return of “territories legally belonging to the Soviet Union” as well as revising the Montreux Convention terms during the “Big Three” Potsdam conference in Berlin in July–August 1945, in discussions with US President Harry Truman and British Prime Minister Winston Churchill. Stalin remarked,
For the position of such a large state as Russia, the question of the Straits is of great importance. The Montreux Convention is wholly directed against Russia, it is a treaty hostile to Russia. Turkey has been granted the right to close the strait to our navigation, not only when there is a war, but also when it seems to Turkey that there is a threat of war, and the question of when this threat arises is decided by Turkey itself. Impossible position! Turkey can always feel that there is some kind of threat, and it can always close the Straits. […] You think that a naval base in the Straits is unacceptable. Well, then give us some other base where the Russian fleet could be repaired, equipped and where it could, together with its allies, defend the rights of Russia. Here is how it goes. But to leave the situation as it is now is ridiculous. I finished.
The British and Russian representatives agreed to look into the possibility of revising the Montreux Convention, perceived as not meeting the conditions of the time, through bilateral negotiations with the Turkish government; but Stalin had overreached. Even as they verbally agreed on the need to review the Montreux Convention, Churchill and Truman diplomatically rejected all of the USSR’s demands for bases in the Straits, along with Soviet claims to Turkish territory.
Stalin’s imperious behavior at Potsdam, his aggressive pressure on Turkey, along with violations of the promises he made to his allies during the war, would eventually backfire in a spectacular manner. Within four years, Turkey would enter the North Atlantic Alliance. The enlargement of NATO subsequently led to the 1955 creation of its Eastern bloc counterpart, the Warsaw Pact. The deepening Cold War would, in turn, increase pressure on all Alliance members, particularly Turkey, that shared maritime and land frontiers with the Soviet Union. Two months after Stalin’s death, on May 30, 1953, the Soviet government, in a diplomatic note, renounced its former territorial claims on Turkey and demands on the Straits in order to strengthen “peace and security.”
The Cold War
Soviet naval developments in the 1960s began to raise Western concerns about the Montreux Convention’s limitations on warships, particularly the potential transit through the Straits of Soviet aircraft carriers built at the USSR’s most advanced naval shipyards in the Black Sea in Ukraine. In 1967, the Soviet navy commissioned what it termed not an aircraft carrier, but an “anti-submarine cruiser” (protivolodochnyy kreyser), christened Moskva. Built in Ukraine’s Nikolaev South (Shipyard No. 444) shipyard, Moskva and its sister ship Leningrad were not true aircraft carriers; instead of fixed-wing aircraft, they carried helicopters to detect submerged US and NATO submarines. While both vessels remained homeported in the Black Sea, the Turks allowed their deployment through the Straits a number of times, on the basis of their Soviet “cruiser” terminology, for voyages in the Mediterranean, the Atlantic and the Indian Ocean. The Soviet government made similar “cruiser” arguments in both 1976 and 1979, and in each instance, Turkey permitted the Soviet navy to pass several more advanced Kiev-class aircraft carriers through the Straits.
The Montreux Convention After the Dissolution of the USSR
The breakup of the Soviet Union devastated Moscow’s Armed Forces, particularly the navy. Russian attempts to rebuild its naval forces were stymied by the fact that the Soviets’ most advanced naval shipyards at Nikolaev (in Ukrainian, Mykolaiv) were now in a new country, Ukraine. Additional irritants in the newly evolving Russian-Ukrainian bilateral relationship quickly became the division of Black Sea warships among the pair and the future status of Sevastopol.
Ukraine became a party to the Montreux Convention in 1992. Joining the treaty was not easy, as according to the Convention’s Article 28, excepting the original signatories, it was open only to the accession of “any state that signed the Lausanne Peace Treaty of July 24, 1923.” Kyiv eventually prevailed in breaking the deadlock by sending a diplomatic note to the government of the French Republic as the depositary of the Convention, stating that Ukraine, as a Black Sea, riparian coastal state, considered itself a party to the 1936 Convention in accordance with international law on the basis of the institution of succession, a position ultimately accepted by the other signatories.
Soon thereafter, the 1994 United Nations Convention on the Law of the Sea (UNCLOS) prompted calls for a revision of the Montreux Convention. However, as Turkey is not a signatory to the UN treaty due to the Eastern Mediterranean country’s longstanding dispute with Greece, the Montreux Convention has remained unaffected.
In subsequent decades, as Russia’s pressure on its neighbors grew, regional NATO aspirants Georgia and Ukraine heightened the Alliance’s concerns about the security situation in the Black Sea. During the August 8–12, 2008, Russian invasion of Georgia, Turkey briefly considered the size and number of US warships it would allow to enter the Black Sea through the Bosporus, when the George W. Bush administration requested the passage of hospital ships USNS Comfort and USNS Mercy, both converted oil tankers, displacing 69,360 tons apiece.
Ankara quickly rejected the request under the terms of Montreux Convention, as, even though they were hospital ships, USNS Comfort and USNS Mercy were US Navy vessels and, accordingly, would violate Montreux’s size limits. This was despite the fact that Turkey, as a NATO member, had supported Alliance programs to train and equip the Georgian Armed Forces. Georgia lost most of its fleet during the August 2008 war but has since provided its remaining bases for NATO ships to use.
The Istanbul Canal
The Istanbul Canal (İstanbul Kanalı) project, linking the Sea of Marmara and the Black Sea via a man-made route parallel to the Bosporus, introduced an element of uncertainty into Turkey’s previously stalwart support for the Montreux Convention. The İstanbul Kanalı was initially described by Turkish President Recep Tayyip Erdoğan as his “crazy project,” when he broached the concept on April 27, 2011, at the Istanbul Congress Center. After letting it stay dormant for seven years, Erdoğan revived the project in 2018. Earlier remarks by Erdoğan that the Istanbul Canal had “nothing to do with Montreux Convention,” raised concerns in some quarters that Turkey was abandoning the treaty or somehow opening it up to revisions. These anxieties have resurfaced periodically even though the construction of a canal adjacent to the Bosporus would do nothing to change the situation of the Dardanelles and the internal Sea of Marmara remaining un-bypassable choke points governed by Montreux.
The proposed Istanbul Canal, originally priced at $9.8 billion, would run to the west of the Bosporus, along a 28-mile (45-kilometer) route through the European part of the city. Despite Erdoğan’s fervent support, the project has run into headwinds of rising and severe domestic opposition, along with the government’s inability to find substantial investment, either domestic or foreign.
It is not a new idea: a canal connecting the Black Sea to the Sea of Marmara was first proposed in the 16th century in the reign of Sultan Suleiman the Magnificent, while in 1994, then–prime minister Bülent Ecevit announced a similar plan for a “second Bosporus.”
Resistance to Erdoğan’s “crazy project” includes environmentalists who warn that building a canal could destroy local water supplies and the regional ecosystem, retired admirals concerned that the project would weaken Turkish sovereignty over the Straits as enshrined in the Montreux Convention, and the liberal political opposition. Istanbul’s popular Republican People’s Party (CHP) mayor, Ekrem İmamoğlu, touted as a potential challenger to Erdoğan, is leading the campaign against the canal, criticizing it as an environmental catastrophe and a financial disaster. Its real cost, he notes, will be more than $75 billion, not the $12.5 billion–15 billion assiduously promoted by Erdoğan.
On April 1, 2021, 126 retired Turkish ambassadors released a statement castigating the project, warning that it could put the Montreux Convention in jeopardy and negatively affect Turkey’s “absolute sovereignty” over the waterways.
The Istanbul Canal will open the Montreux Convention for discussion. Atatürk’s Turkey’s greatest diplomatic success after the Treaty of Lausanne, the Montreux Convention, if opened to discussion, would lead to the loss of Turkey’s absolute sovereignty over the Istanbul–Çanakkale [fort city guarding the Mediterranean Sea–side entrance to the Dardanelles] Straits and the Sea of Marmara. […] Our ally, the USA, which is not a party to the Montreux Convention and sees the Convention as an obstacle to its entry to the Black Sea as it wishes, has been trying for years to eliminate Montreux or to make a new contract to which it will be a party. The Istanbul Canal […] will serve the USA’s purpose of opening Montreux to discussion. Opening the Montreux Convention for discussion will lead to Turkey imperiling its vital sovereignty and security advantages from the treaty, in short, a real survival problem, which may cause Turkey to lose all these gains. The Istanbul Canal, which will serve the interests of states with various ambitions on the Republic of Turkey, should be abandoned.
Worse was yet to come: three days after the retired ambassadors’ declaration, an open letter appeared, signed by 104 retired admirals, further criticizing Erdoğan’s megaproject for its alleged threat to the Montreux Convention. The admirals wrote,
The Turkish Straits are one of the most important waterways in the world and have been managed according to multinational agreements throughout history. Montreux, which is the last of these treaties, protects Turkey’s rights in the best way: It is not only a contract regulating the passage through the Turkish Straits but also a great diplomatic victory that completes the Lausanne Peace Treaty, which restored Turkey’s full sovereignty over Istanbul, Çanakkale, the Sea of Marmara and the Straits. Montreux is the basic document of the security of the Black Sea riparian countries and is the convention that makes the Black Sea a sea of peace.
Montreux is a convention that prevents Turkey from unintentionally entering the war on the side of one of the warring parties in any war. Montreux enabled Turkey to maintain its neutrality in World War II. For these and similar reasons, we believe that all kinds of discourses and actions that may cause the Montreux Convention, which has an important place in Turkey’s survival, to be discussed/to be brought to the table, should be avoided.
The admirals’ mutiny caused an uproar among Justice and Development Party (AKP) government officials, who said it harkened back to coup times of Turkey’s past; several signatories were subsequently arrested. Nevertheless, the opposition seems to have had an effect, as the day after the admirals’ letter appeared, as part of his ongoing efforts to drum up foreign investment for his Istanbul Canal project, Erdoğan remarked, “Turkey does not currently intend to withdraw from the Montreux Convention,” adding that his government would continue to implement the agreement until it found an opportunity to “improve” it.
Erdoğan’s bland assurances about Montreux Convention did not convince Putin. Five days after Erdoğan promoted his Istanbul Canal project, the Russian president had a telephone conversation with him, during which Putin remarked that despite Turkey’s intention to build the Istanbul Canal, it was important to preserve the 1936 Montreux Convention Regarding the Regime of the Straits, as it was integral to ensuring regional stability and security.
Seemingly oblivious to domestic and international criticism, on June 26, 2021, Erdoğan officially inaugurated the İstanbul Kanalı venture, whose projected cost had now risen to an estimated $15 billion. The success of Erdoğan’s latest mega-project currently seems problematic at best. He has launched it at a time when the Turkish economy faces many challenges. Turkey’s tensions with the European Union and the United States and its record-high levels of foreign debt have so far deterred most Turkish and foreign lenders from the project.
Russian Invasion of Ukraine and the Role of the Straits in 2022
“It is a wide road that leads to war, but only a narrow path leads home again.” – Russian proverb
The Run-Up to the War
With 20/20 hindsight, perhaps the most startling aspect of Putin’s February 24, 2022, assault on Ukraine was how foreign intelligence, particularly those in the US, the UK and NATO, all reported on the months-long buildup of Russian forces on its territory with Ukraine, as well as naval deployments to the Black Sea region. Government officials and analysts even had access to commercial satellite imagery that tracked the seemingly relentless massing of Russian forces. Putin and Russian Defense Minister Sergei Shoigu repeatedly dismissed Western concerns by stating that the military buildup was only in preparation for long-planned military exercises. A further element downplaying the intelligence was that the expected day for the beginning of Russia’s military operation was repeatedly delayed.
Continuing its policy of maskirovka about Putin’s true intentions, the Russian Ministry of Defense announced on January 20 the start of a series of naval maneuvers involving more than 140 ships and vessels and over 10,000 military personnel. The exercises, under the general supervision of the commander-in-chief of the Russian Military-Maritime Fleet (Voyenno-Morskoy Flot—VMF) Nikolai Evmenov, would be held in waters adjacent to Russian territory as well as operationally important ocean areas, including the Mediterranean, Arctic, Sea of Okhotsk, in the northeastern Atlantic and Pacific. Ten days later, the secretary of the Security Council of the Russian Federation, Nikolai Patrushev, repeated that Russia supposedly does not want to fight with Ukraine and that there was no threat from Moscow.
Ironically, the week before the Russian Ministry of Defense announced its upcoming naval drills, a conference on planning the 2022 Ukrainian-US Sea Breeze exercise was held in Odesa. The 2021 iteration of these exercises was the largest in more than 20 years, involving 32 warships, 40 aircraft and 5,000 personnel from 17 NATO member states and partners. More than 60 countries and international organizations were invited to participate in the 2022 exercise.
That said, there were prescient observers warning of the consequences before the conflict began. Four days before the outbreak of hostilities, Ukraine’s ambassador to Turkey, Vasil Bodnar, observed that Russia’s aggressive actions toward Ukraine since 2014 effectively destroyed regional cooperation in the Black Sea, in particular within the framework of the Organization of the Black Sea Economic Cooperation (BSEC) and the Black Sea Naval Cooperation Group (BLACKSEAFOR). Bodnar said,
We had not only the BSEC, but also the BLACKSEAFOR format, which created a security environment in the region and created conditions for interaction and trust between the fleets. Since 2014, this has become impossible. We cannot take part in events where there is a Russian fleet. The situation is the same with Georgia, which does not recognize the Russian occupation and still has no diplomatic relations with Russia since 2008.
Bodnar presciently concluded, “The situation in the region is already unstable, and decisive action must be taken to prevent it from escalating into an armed conflict.”
On January 30, General (ret.) Benjamin Hodges, a former commander of US Army Europe, stated during a UK-based LBC channel broadcast that rising tension between Russia and Ukraine had an “80 percent chance” of erupting into a full-blown conflict by the end of February. Hodges offered his views on changing the military dynamics in the Black Sea and the possible role that the Montreux Convention could play in ameliorating the violence, commenting, “Actually, there is a trump card that we can use against Russia, but we do not use. This is Turkey’s control over the Straits. Turkey has legitimate reasons to close the straits to Russian military ships if we establish the right relationship with our Turkish allies to make sure they are not subject to Russian backlash.” When queried if the issue had been raised with Turkey, Hodges replied, “I asked US National Security Advisor Jack Sullivan about this two weeks ago. As far as I understand, they are talking about this with our allies.”
The Turkish government, however, denied Hodges’ observations as well as subsequent public assertions that Russia had violated the Montreux Convention by passing warships through the Straits; and Ankara plainly rejected recommendations on social media that the Turks should close the Straits to Russian warships because of the purported infractions. Turkish diplomatic sources, meanwhile, strongly asserted that there were no negotiations with the US on the Montreux Convention, that all maritime passages through the Turkish Straits until then strictly adhered to the Montreux Convention’s stipulations, and that there had been no change in Turkey’s stance.
With tensions rising, two days before the outbreak of war, Erdoğan offered to host a face-to-face summit between Putin and his Ukrainian counterpart, President Volodymyr Zelenskyy, or a “technical meeting” between Ukrainian and Russian officials. Turkey’s offer was perceived by some observers as no more than an image-building exercise for Erdoğan, whose domestic standing was deteriorating amid domestic economic turmoil. At the same time, Russia notably supplies nearly half of Turkey’s natural gas and two-thirds of its wheat imports—surely an important consideration for Ankara.
February 24—Putin’s “Special Military Operation” Begins
Despite being heavily outgunned, the Ukrainian Armed Forces were in a stronger position on the eve of Putin’s declared invasion, on February 24, 2022, than they were in their initial encounter with Russia eight years earlier. Since its 2014 loss of Crimea to a Russian military invasion and subsequent occupation and annexation, Ukraine tripled its defense budget and strove to modernize its military, both to defend against Russia but also to comply with NATO’s entrance standards.
On February 24, Ukraine sent Turkey an official request to implement the Montreux Convention. A number of media outlets mistakenly then reported that Turkey had acceded to the request.
The Russian large-scale offensive elicited an immediate response the same day from NATO Secretary General Jens Stoltenberg, who said that North American and European alliance members had already deployed thousands more troops to eastern NATO member states and had placed more on standby, remarking, “We have over 100 jets [on] high alert protecting our airspace and more than 120 allied ships at sea from the high north to the Mediterranean. […] We will continue to do whatever is necessary to shield the alliance from aggression.”
Despite Stoltenberg’s forceful assertions, the reality is that over the past several years visits by NATO warships (from non-littoral member state navies) to the Black Sea have been quite irregular. In 2019 and 2020, no NATO warships visited the Black Sea. In 2021 the number of NATO naval vessels visiting the Black Sea surged to 31, the same number as in 2014 and the highest annual level since Russia occupied Crimea. Ships from the US 6th Fleet, headquartered in Naples, accounted for 13 of this number, followed by Spain (5), the UK (3), Italy (3), Greece (3), France (3) and the Netherlands (1).
Starting in November 2021 and continuing to the end of the year, there was an uptick in NATO activity in the Black Sea, as five non-littoral Alliance member warships passed the Straits to operate there for 21 days under the Montreux Convention terms—four from the US Navy’s 6th Fleet and one French warship. These were the USS Porter (DDG 78) and USS Arleigh Burke (DDG 51) guided missile destroyers, the USS John Lenthall (T-AO-189) oiler, the 6th Fleet’s flagship and command ship USS Mount Whitney (LLC 20), and the French Navy’s FS Auvergne (D 654).
Despite the rise in regional Russian-Ukrainian tensions, the departure of NATO’s last non-local warship, FS Auvergne (D654), from the Black Sea, on January 2, 2022, led Ukraine’s Institute for Black Sea Strategic Studies to observe, “…at the time when the Russian military threat to Ukraine has dramatically escalated in January 2022, warships of the non–Black Sea NATO have been absent in the Black Sea for 21 days, obviously increasing the risk of aggression from the sea over the holidays.” The Institute’s data shows that beginning with Russia’s aggression against Ukraine in 2014, the largest contributor to NATO’s subsequent Black Sea deployments was provided by the 6th Fleet, undertaking 76 out of NATO’s 191 warship visits since then, roughly 40 percent.
NATO’s torpor and relative inaction was matched by a lack of signaled resolve from Washington as to its willingness to remain physically involved. During a press conference in Romania on October 20 with Romanian Minister of Defense Nicolae-Ionel Ciucă, US Secretary of Defense Lloyd Austin was asked, “What is the US commitment to the Black Sea region?” The Pentagon head’s reply underscored the importance of Black Sea security to US interests while, conspicuously, avoiding any mention of plans to boost or maintain US presence there:
Security and stability of the Black Sea are in the U.S. national interest and are critical to the security of NATO’s Eastern Flank. It goes without saying that the region is vulnerable to Russian aggression, and we have seen evidence of that by ongoing actions in Eastern Ukraine, occupation of parts of Georgia, militarization of the Black Sea, and provocative actions in the air and at sea. I would go further and say that Russia’s destabilizing activities in and around the Black Sea reflect its ambitions to regain a dominant position in the region and to prevent the realization of a Europe that is whole, free and at peace. And so, again, the Black Sea region is in the U.S. national interest, and we will stay focused on it, and we will continue to work with our partners in the region.
Complicating matters for NATO was the fact that the possibility of providing potential maritime assistance to Ukraine remained uncertain until Turkey clarified its position on the war. Since the onset of the conflict, Turkey upheld strict neutrality, even though the government was in fact considering its options to close the Straits under the Convention’s articles. Speaking to journalists on February 20, while attending the Munich Security Conference, just days before the outbreak of hostilities, Turkish Defense Minister Hulusi Akar hedged his bets and noted that Turkey successfully fulfills all its responsibilities within NATO, continuing, “It is our most sincere wish that the countries bordering the Black Sea live there in comfort, safety and prosperity. In this sense, we also express here that the Montreux Convention is important, the necessary support should be provided, and the order provided by the Montreux Convention is beneficial for all parties.”
While NATO waited on the Turkish government’s decision about the Straits, it had other maritime assets in its Black Sea coastal members Bulgaria and Romania, whose improvement had been closely noted by Russia. In November 2020, for example, Russian Navy Captain 1st rank Vasily Dandykin observed, “Romania, although one of the poorest countries in Europe, pays great attention to the development of its Navy. They receive new corvette-class ships. Its own shipbuilding industry is developing, in contrast to Ukraine’s. That is, the Romanian fleet today is objectively more powerful than the Ukrainian or Bulgarian.”
The first indication that a shift on Montreux in Ankara was possible came on February 26, when Turkey’s Foreign Minister Mevlüt Çavuşoğlu publicly evaluated Ukraine’s request for assistance under the terms of the Convention, stating,
In this critical period, we will implement all the Montreux Convention’s articles to the letter, just as we did before. […] The provisions of the Montreux Convention are very clear and precise. If Turkey is in a war, all the passages subsequently are completely under the control of Turkey. If Turkey is not a party to a war and there are warring parties, Article 19 clearly states it. This applies to the ships of warring countries. It authorizes Turkey to close the passage through the Straits, but again, Article 19 gives an exception. This applies not only to Russia, but to all littoral countries. This also applies to Ukraine.
The Ukrainian president immediately expressed his gratitude, tweeting, “I thank my friend Mr. President of TR @RTErdogan and the people of TR for their strong support. The ban on the passage of RU warships to the Black Sea and significant military and humanitarian support for UA are extremely important today. The people of UA will never forget that!” Both the Russian and Ukrainian governments were well aware that the Turkish implementation of the Montreux Convention’s Article 19—forbidding the passage of the warring parties’ (that is, specifically Russia’s and Ukraine’s) warships through the Straits, except for the one-time return of ships to their home ports—could significantly impact Russian force projection into and from the Mediterranean. By activating Article 19, Turkey had effectively bottled up Russia’s Syrian squadron (eskadra) on the south side of the Straits, preventing it from actively assisting operations in the Black Sea if the restrictions lasted for even a few weeks.
Events now began to move quickly. The next day, Çavuşoğlu appeared live on CNN Türk and officially announced that Turkey would exercise its sovereignty under terms of the Montreux Convention and restrict the passage of Russian warships into the Black Sea due to its “war” in Ukraine. Çavuşoğlu said that since Russia’s unprovoked military “operation” had turned into a “war,” “Under these conditions, we will apply the Montreux Convention. Article 19 is quite clear. At first it was a Russian attack, and we assessed it with experts, soldiers, lawyers. Now it has turned into a war. It is not a military operation; it is officially a state of war.” As noted above, according to Article 19, warships of belligerent states are not allowed to pass through the Straits. Despite the ban on passage, warships of warring states, both coastal and non-coastal, separated from their bases, may return to these bases. Nevertheless, Çavuşoğlu added, without explaining his government’s legal reasoning further, that the passage plan not only included Russian warships but also Black Sea littoral and foreign naval units as well.
Some had a more expansive view of the role of the Montreux Convention. The same day that Çavuşoğlu spoke, the director of Ukraine’s Center for Army Studies, Conversion and Disarmament, Valentin Badrak, remarked that not everyone views Turkish actions under the Montreux Convention as neutral. To him, it was a precursor to the formation of an anti-Russian alliance. According to Badrak, “The West is imposing sanctions on Putin and his circle, including Gen. [Valery] Gerasimov [the Russian chief of the General Staff]. Turkey has closed off the Bosporus and Dardanelles and does not let Russian warship into the Black Sea. Effectively, we are watching an anti-Putin coalition being formed.”
Even as Turkey exercised its sovereign right under the Montreux Convention, on March 1, Erdoğan’s spokesperson İbrahim Kalın said, during an interview with CNN Türk, “We must act with our country’s priorities in mind. There must be a party capable of negotiating with Russia. Who will talk to Russia when everyone burns bridges? We do not plan to impose sanctions to keep this channel open.”
Ankara now put its sovereignty over the Straits into action; the same day that Kalın spoke, Çavuşoğlu told national broadcaster Habertürk TV that Turkey had asked Russia not to request sending its warships through the Straits even before the Turkish government labeled Russia’s “special military operation” invasion of Ukraine a “war” and implemented Article 19 of the Montreux Convention. Çavuşoğlu said, “Russia said four of its ships would cross the Straits on February 27–28, three of which are not registered to bases in the Black Sea. We told Russia not to send these ships, and Russia said the vessels would not cross the Straits. Nobody should be offended by this, because the Montreux Convention is valid today, yesterday and tomorrow, so we will implement it.”
One immediate result of Turkey invoking Article 19 was to effectively maroon the Russian naval units concentrated off Tartus, Syria, which were tasked with deterring US and NATO carrier groups in the Eastern Mediterranean. At the same time, those Russian eskadra vessels could not pass northward through the Straits and augment Russian naval units assisting ground operations against Ukraine. The stranded ships included the Slava-class cruisers RTS Marshal Ustinov (055) and RFS Variag (011), two Udaloi-class destroyers, two guided-missile frigates, two Kilo-class diesel-electric attack submarines, a Buian-class corvette, two assault boats and a variety of auxiliary vessels—all effectively sidelined from participating in Ukrainian operations by Turkey’s actions.
While the Russian government was undoubtedly disappointed by Turkey’s rejection of its request to pass the above-mentioned quartet of warships into the Black Sea, it nevertheless was mindful of the Montreux Convention’s similarly prophylactic potential to prevent a NATO naval “surge” into the Black Sea beyond the Convention’s restrictions on non–Black Sea powers, further bolstering Moscow’s consistent support for the treaty. On March 2, Russia’s ambassador to Ankara, Aleksei Erkhov, stated during a television interview, “I have to say that we appreciate [Turkey’s] stance toward the protection and compliance of the Montreux Convention, which is an important international law document. I believe that together we can come to a situation where all our interests and all our desires can come true.”
The Russian Assault From the Sea and Naval Losses
While initial media coverage focused on the Russian military’s aerial and ground assaults, the conflict has also had a notable naval component. On February 27, the General Staff of the Ukrainian Armed Forces reported that the Russian military was expanding its maritime operations, which included at least two attempts to land on Ukraine’s Black Sea coast. All were successfully repulsed, during which the Russian navy lost two boats and ships.
Nevertheless, the Russian re-invasion has included attacks from the sea on Ukraine’s Black Sea cities of Odesa, Ochakov and Mariupol. One of the first casualties in the conflict was the flagship of the Ukrainian Navy, the 30 year-old Krivak-class frigate Het’man Sagaidachnii, scuttled at the Nibulon ship repair plant in Mikolaiv, on February 24, to avoid being captured by the Russians. In Russia’s 2014 Crimea operation, Het’man Sagaidachnii avoided capture by being out of the theater of operations, returning from an international anti-piracy deployment off Somalia. Subsequently homeported in Odesa, after Ukraine lost Sevastopol, the frigate ended up at the Nibulon facility on July 2021, in preparation for an extensive refit that the Ukrainian Navy hoped would have given the ship another decade of useful service.
The conflict has also created logistical problems for Russian VMF warships operating in the Eastern Mediterranean. On March 5, five Russian naval vessels attempting to access refueling facilities in Limassol, Cyprus, were refused entry because of Russia’s attack on Ukraine. Cyprus, in solidarity with all other European Union members, banned Russian ships from entering their ports. The Cypriot foreign ministry in Nicosia informed Russia with a note verbale that due to the ongoing conflict in Ukraine, their bilateral agreement on providing facilities and mooring permits would be suspended until further notice.
Three weeks into the war, Ukraine struck a significant blow against the Russian navy. On April 13, a Ukrainian concealed coastal missile battery fired two Neptun subsonic sea-skimming cruise anti-ship missiles at the Russian Black Sea Fleet’s flagship, the 39-year-old Slava-class cruiser Moskva patrolling around 60 nautical miles south of Odesa, in the vicinity of Snake Island. While Ukraine maintained that its missiles struck the Moskva, Russia insisted that the warship was heavily damaged by fire, not a Ukrainian missile strike, before it sank while under tow in rough seas. Reportedly, other Russian naval vessels operating in the area quickly moved further away from the Odesa coast.
Summing up the Russian VMF’s position in the Black Sea after the loss of the Moskva, on April 28, the British Ministry of Defense tweeted, “Approximately 20 Russian Navy vessels are currently in the Black Sea operational zone, including submarines. The Bosporus Strait remains closed to all non-Turkish warships, rendering Russia unable to replace its lost cruiser Moskva in the Black Sea [Emphasis added]. Despite the embarrassing losses of the landing ship Saratov and cruiser Moskva, Russia’s Black Sea Fleet retains the ability to strike Ukrainian and coastal targets.”
Codified by the 1936 Montreux Convention, Turkish sovereign control over the Straits continues to the present, though not without significant challenges, both internal and external.
Whatever the eventual outcome of the Russian-Ukrainian conflict, it is likely to increase calls to revise the Montreux Convention, both within Turkey and beyond. The CHP (Kemalist) opposition party’s leader, Kemal Kılıçdaroğlu, two days before the Kremlin launched its massive assault, reaffirmed his faction’s continuing stalwart support for the nearly 90-year agreement in its current form, remarking at a party conference, “To explain what a betrayal it is to open the Montreux Convention for discussion: Montreux has an extremely important meaning for the security of the world. If someone who does not know history or cannot read the world opens Montreux for discussion, they should know the consequences.”
Between the ultimate fate of the Istanbul Canal and the aftermath of the Russian-Ukrainian war, an additional potential element for consideration in any possible revision of the Montreux Convention’s articles will be the singularly unique naval advantage that Russia currently maintains over the other five Black Sea littoral states. Namely, this is Moscow’s ability to quickly supplement its naval forces in the Black Sea by bringing elements of the Caspian Flotilla in via the Volga–Don Canal, classified under international maritime law as a Russian “internal waterway.” Notably, in a show of strength a week prior to the re-invasion, on February 17, about 20 Caspian Flotilla warships departed from their home port in Makhachkala, Dagestan, to the Black Sea basin participate in the Russian navy’s global “Training Plan for the Armed Forces of the Russian Federation for 2022,” whose opening exercises began in January.
This advantage was demonstrated again during the present Russo-Ukrainian war, when Caspian Flotilla vessels launched 3M-54 Kalibr cruise missiles to support operations in Ukraine. With an estimated range of around 932–1,553 miles (1,500–2,500 km), the missile has become a mainstay in the Russian VMF’s ground-strike capabilities. Since the Volga-Don Canal is internationally recognized as an “internal Russian waterway,” the Caspian Flotilla’s maritime assets remain beyond the range of non-Caspian littoral navies’ surface assets while allowing its of warships to become mobile missile strike platforms with little fear of retaliation, as first evidenced in the Flotilla’s 2016 Syrian Kalibr missile attacks to those more recently launched against Ukrainian targets.
Since World War II, the United States increasingly came to believe that that the Montreux Convention has given an unfair advantage to, particularly, Soviet/Russian Black Sea naval forces. And this issue has risen to the forefront yet again, as NATO and the US have struggled to figure out how to sufficiently supply and support Ukraine in its war against Russia as well as protect maritime security in the Black Sea basin.
Even though the US was not a signatory to the Montreux Convention, amendments could be pursued under the international legal practice of “Clausula rebus sic stantibus,” one of the oldest norms of customary international law, which provides for the unenforceability of an international convention, agreement or treaty due to fundamentally changed circumstances. Indeed, a variant of this doctrine is codified in Article 62 of the Vienna Convention on the Law of Treaties and is generally contained as a provision in individual treaties. Bolstering the argument that such an option could apply in this case, two of the signatory states since the Montreux Convention was signed have disappeared, fracturing into smaller, independent, sovereign countries—the Soviet Union and Yugoslavia.
Unrest in the Black Sea seems likely to continue as long as neo-imperial Russia maintains the means to fiercely block Ukraine’s pro-European and pro-democratic course, on the one hand, and the Euro-Atlantic community preserves its political will to keep backing Kyiv, on the other hand. All the while, the Montreux Convention continues to play its dual roles as both referee and goalkeeper.
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 “Сі-Бриз-2022: прикордонники візьмуть участь у морській, сухопутній та авіаційній компонентах,” Адміністрація Державної прикордонної служби України, 13 січня 2022, https://www.kmu.gov.ua/news/si-briz-2022-prikordonniki-vizmut-uchast-u-morskij-suhoputnij-ta-aviacijnij-komponentah.
 “Rosiya ahresyvnymy diyamy znyshchyla rehionalʹnu spivpratsyu u Chornomu mori – posol,” Ukrinform, February 20, 2022, https://www.ukrinform.ua/rubric-world/3407854-elizaveta-ii-zarazilasa-koronavirusom.html.
 “Rosiya ahresyvnymy diyamy,” Ukrinform, February 20, 2022.
 Aurora Bosotti, “Russia-Ukraine row in ‘80% chance’ of erupting into all-out war ‘Only Germany can stop it,’” The Daily Express, January 30, 2022, https://www.express.co.uk/news/world/1557787/Russia-Ukraine-war-warning-US-Army-Europe-Ben-Hodges-Germany-vn.
 Huseyin Hayatsever, “Rusya-Ukrayna gerilimiyle birlikte Batı, gözünü boğazlara çevirdi,” Cumhuriyet Gazetesi, 15 Şubat 2022, https://www.cumhuriyet.com.tr/turkiye/rusya-ukrayna-gerilimiyle-birlikte-bati-gozunu-bogazlara-cevirdi-1908023.
 Nazlan Ertan, “Erdogan calls Russia’s recognition of Ukrainian breakaways ‘unacceptable,’” Al-Monitor, February 22, 2022, https://www.al-monitor.com/originals/2022/02/erdogan-calls-russias-recognition-ukrainian-breakaways-unacceptable.
 Frank Ledwidge, “The insurgency to come in Ukraine,” The Asia Times, February 26, 2022. https://asiatimes.com/2022/02/the-insurgency-to-come-in-ukraine/.
 “Туреччина закриває Босфор і Дарданелли для військових кораблів,” Укрінформ, 27.02.2022, https://www.ukrinform.ua/rubric-world/3415014-tureccina-zakrivae-bosfor-i-dardanelli-dla-vijskovih-korabliv.html.
 “Press briefing by NATO Secretary General Jens Stoltenberg following an extraordinary meeting of the North Atlantic Council,” NATO, February 24, 2022, https://www.nato.int/cps/en/natohq/opinions_192408.htm.
 Тетяна Гучакова, Андрій Клименко, Ольга Корбут, “Перешкоди судноплавству в Азовському морі. Моніторинг утримання суден в Керченській протоці на 1 грудня 2021,” Інститут Чорноморських стратегічних досліджень, 11.12.2021, https://www.blackseanews.net/read/182620.
 “Перебування військових кораблів нечорноморських країн НАТО в Чорному морі у листопаді–грудні 2021 року,” Інститут Чорноморських стратегічних досліджень, 14.12.2021, https://www.blackseanews.net/read/182759.
 “Перебування військових кораблів нечорноморських країн НАТО в Чорному морі за 2021 та у січні 2022,” Інститут Чорноморських стратегічних досліджень, 14.12.2021, https://www.blackseanews.net/en/read/184110.
 “Secretary of Defense Lloyd J. Austin III’s Remarks at Romanian Ministry of Defense Post-Bilat Joint Press Event,” Bucharest, U.S. Embassy in Romania, October 20, 2022, https://ro.usembassy.gov/secretary-of-defense-lloyd-j-austin-iiis-remarks-at-romanian-ministry-of-defense-post-bilat-joint-press-event/.
 “Milli Savunma Bakanı Akar, Münih’te gazetecilere değerlendirmelerde bulundu,” Demirören Haber Ajansı, 20.02.2022, https://www.haberler.com/milli-savunma-bakani-akar-munih-te-gazetecilere-14746473-haberi/.
 Сергей Вальченко, “Капитан оценил возможность войны за Крым с Украиной и Турцией,” Московский Комсомолец, 26.11.2020, https://www.mk.ru/politics/2020/11/26/kapitan-ocenil-vozmozhnost-voyny-za-krym-s-ukrainoy-i-turciey.html.
 “Dışişleri Bakanı Çavuşoğlu: Montrö Anlaşması’nı tüm maddeleriyle beraber bu kritik süreçte uygulayacağız,” T24 Bağımsız İnternet Gazetesi, 26 Şubat 2022, https://t24.com.tr/haber/disisleri-bakani-cavusoglu-ndan-ukrayna-daki-turkiye-cumhuriyeti-vatandaslarinin-tahliyesine-iliskin-aciklama,1017478.
 Володимир Зеленський @ ZelenskyyUa, Twitter, 2/26/22, 8:27 AM, https://twitter.com/ZelenskyyUa/status/1497564078897774598?ref_src=twsrc%5Egoogle%7Ctwcamp%5Enews%7Ctwgr%5Etweet.
 “Dışişleri Bakanı Çavuşoğlu CNN TÜRK’te: Temennimiz kalıcı ateşkes,” CNN Türk, 17:06, 27.02.2022, https://www.cnnturk.com/dunya/son-dakika-rusyanin-saldirilarinda-son-durum-rus-heyeti-muzakereler-icin-belarusta.
 Servet Uzun, “Son Dakika: Bakan Çavuşoğlu’ndan Montrö açıklaması: Tüm ülkeleri boğazlardan savaş gemisi geçirmemesi konusunda uyardık,” Dünya, 28.02.2022, https://www.haberler.com/son-dakika-bakan-cavusoglu-ndan-montro-14763965-haberi/.
 Валентин Бадрак, “Под Путиным зашаталось кресло, или Что свидетельствует о желании президента РФ выйти из игры,” Главред, 27 февраля 2022, https://opinions.glavred.info/pod-putinym-zashatalos-kreslo-ili-chto-svidetelstvuet-o-zhelanii-prezidenta-rf-vyyti-iz-igry-10347734.html.
 “Ukrayna’ya Rusya işgalinde Türkiye hangi adımları atacak? İbrahim Kalın CNN TÜRK’te,” CNN Türk, 01.03.2022, https://www.cnnturk.com/video/turkiye/ukraynaya-rusya-isgalinde-turkiye-hangi-adimlari-atacak-ibrahim-kalin-cnn-turkte.
 “Dışişleri Bakanı Mevlüt Çavuşoğlu: 3 Rus gemisine izin vermedik,” Habertürk TV, 01.03.2022, https://www.haberturk.com/son-dakika-disisleri-bakani-cavusoglu-dan-haberturk-tv-de-aciklamalar-3361267.
 Sam LaGrone, “Russian Navy Masses 16 Warships Near Syria,” USNI News, February 24, 2022, https://news.usni.org/2022/02/24/russian-navy-masses-16-warships-near-syria.
 “Rus Büyükelçi: Türkiye’yi Montrö tutumu nedeniyle takdir ediyoruz,” Habertürk TV, 02.03.2022, https://www.haberturk.com/rus-buyukelciden-turkiye-ye-tesekkur-3362485.
 “Україна відбила дві спроби морського десанту РФ – Генштаб ЗСУ,” Діфенс Експрес, 27 лютого 2022, https://defence-ua.com/news/ukrajina_vidbila_dvi_sprobi_morskogo_desantu_rf_genshtab_zsu-6229.html.
 Анна Шиканова, “’Так треба.’ Флагман ВМС ‘Сайгадачний’ підтопили в Миколаєві в перший день війни,” РБК-Україна, 03 Березня 2022, https://www.rbc.ua/ukr/news/tak-nuzhno-flagman-vms-saygadachnyy-podtopili-1646343826.html.
 “ ‘Гетьман Сагайдачний’ може ‘застрягти’ на ремонті на невизначений період,” Діфенс Експрес, 15 лютого 2022, https://defence-ua.com/people_and_company/getman_sagajdachnij_mozhe_zastrjagti_na_remonti_na_neviznachenij_period-6130.html.
 Annie Charalambous, “Cyprus forbids mooring of five Russian navy ships this week due to Ukraine war,” Philenews, March 5, 2022, https://in-cyprus.philenews.com/cyprus-forbids-mooring-of-five-russian-navy-ships-this-week-due-to-ukraine-war/.
 “Voyennyye moryaki uvideli misticheskiy sled v potere kreysera ‘Moskva,’ ” Moskovskiy Komsomolets, April 15, 2022, https://www.mk.ru/politics/2022/04/15/voennye-moryaki-uvideli-misticheskiy-sled-v-potere-kreysera-moskva.html.
 Heather Mongilio, “UPDATED: Russia Says Damaged Cruiser Moskva Sank Under Tow Headed to Black Sea Homeport,” USNI News, April 13, 2022, https://news.usni.org/2022/04/13/russian-navy-confirms-severe-damage-to-black-sea-cruiser-moskva-crew-abandoned-ship.
 Kirstie McCrum, “Twenty Russian warships and submarines gather in Black Sea, MOD reports,” Wales Online, April 28, 2022, https://www.walesonline.co.uk/news/world-news/twenty-russian-warships-submarines-gather-23808668.
 “CHP lideri Kılıçdaroğlu’ndan Montrö uyarısı,” Habertürk, 22 Şubat 2022, https://www.haberturk.com/son-dakika-chp-lideri-kilicdaroglu-ndan-aciklamalar-3352835.
 “Разнородная группировка корабельных сил Каспийской флотилии вышла в море для участия в плановом учении,” Новости, Министерство обороны Российской Федерации, 17.02.2022, https://function.mil.ru/news_page/country/more.htm?id=12409275@egNews.
 “Оперативна інформація станом на 10.00 27 лютого 2022 року щодо російського вторгнення,” Генеральний штаб ЗСУ, Twitter, 27 лютого 2022, https://www.facebook.com/GeneralStaff.ua/posts/260463059600113.
 See Bulent Gokcicek, The Montreux Convention regarding the Turkish Straits and its importance after the South Ossetia war, Naval Postgraduate School, Monterey, California, Masters thesis, March 2008, pp. xvi, 77, https://apps.dtic.mil/sti/pdfs/ADA496759.pdf.
 Elihu Lauterpacht, International Law: Disputes, War and Neutrality, pts. IX-XIV, Cambridge: Cambridge University Press, 2004, pp. 804.