Recent headlines on Northeast Asian maritime affairs have focused on Beijing’s claim that the Taiwan Strait should not be considered international waters based on the principle that Taiwan is Chinese territory (Huanqiu Shibao, June 23; Liberty Times, June 23; JongangIlbo, June 20). With international attention focused on Taiwan, the South Korea-China Maritime Cooperation Dialogue meeting on June 17 went largely unnoticed (Yonhap News, June 17; People.cn, June 17). The dialogue, which was launched in 2021, promotes cooperation on maritime issues in the Yellow Sea. The meeting was hosted by the South Korean and Chinese foreign ministries, but also included each country’s coast guard, defense ministry, and several other relevant government agencies.
Several points of contention between South Korea and China exist in the Yellow Sea, including unresolved maritime boundary delimitation, frequent illegal fishing by Chinese vessels, disagreement over the status of Socotra Rock (an underwater reef known as Ieodo in Korean), and Chinese military assertiveness.  Beijing is in no hurry to resolve these matters, but Seoul is less patient. China apparently believes that time is on its side, and officially declares that it has no serious maritime issues with South Korea in the Yellow Sea. By contrast, South Korea is concerned about China’s coercive attitude toward its weaker neighbors, and expects China’s naval influence to become stronger, putting Korea at an increasing disadvantage. Moreover, the South Korean Navy, Coast Guard, and even civilian fishermen report daily encounters with Chinese naval and fishing vessels in the Yellow Sea (KBS News, October 16, 2021; Financial News, April 18, 2022).
The eastern seaboard of China abuts four seas, the northernmost of which is the Yellow Sea (known as “the West Sea” in Korean), which is perhaps the most vital to China from both a security and economic perspective. The geographical position of the Yellow Sea, with the large port city of Tianjin on its western edge is only 120 kilometers from Beijing, which makes it a critical area in terms of security. Despite the strategic importance of the Yellow Sea, it has not attracted much external attention. This article discusses three key issues concerning the Yellow Sea that are poorly understood:
- Historical background and current perceptions concerning the Yellow Sea’s strategic value to China;
- China’s current actions in the Yellow Sea;
- Policy options for responding to China’s increasing assertiveness in the Yellow Sea.
The Weight of History
In China’s official narrative, the period from the mid 19th to the early 20th century is regarded as a historical nadir, an era that is known as the “century of humiliation.” During that time, China fell victim to foreign colonial powers that leveraged their naval superiority to project force on to the Chinese Mainland and compel the Qing dynasty to make concessions through a series of “unequal treaties” (不平等条约, bu pingdeng tiaoyue).
A decisive event in China’s decline was the Sino-Japanese War (1894-1895), which also involved Korea’s Chosun dynasty. In September 1894, the Qing dynasty’s Beiyang Fleet was soundly defeated by the Japanese navy in the Battle of the Yellow Sea. Then, in 1900, during the Boxer Rebellion, the foreign legations in Beijing came under siege. In response, a multilateral force of eight countries led by Great Britain passed through the Yellow Sea to land at Tianjin, and later entered Beijing. This Western pressure was an essential factor in the subsequent collapse of the Qing Dynasty.
In April 2019, President Xi Jinping attended a ceremony at Qingdao, a city that was once a German treaty port, to commemorate the 70th anniversary of the founding of the People’s Liberation Army (PLA) Navy. For Xi, marking China’s burgeoning naval power on the Yellow Sea sent a signal that by “striving to build the PLA Navy into a world class navy in an all-around way,” China had overcome its tragic legacy of past defeats at the hands of foreign powers (Xinhuanet, April 23, 2019).
Historical experience frames the current security perspective of the Chinese government, particularly its goal of preventing foreign powers from entering the Yellow Sea. Two cases in 2003 and 2010, respectively, illustrate the Chinese attitude. In 2003, then North Korean leader Kim Jong-il tried to stimulate his country’s economy by opening up several ports to the outside world: Chongjin and Rajin on the eastern coast of North Korea, and Sinuiju on the western coast. Sinuiju is a port city on the border between China and North Korea, and China did everything possible to obstruct its opening. When North Korea appointed Chinese businessman Yang Bin as chief executive of the Sinuiju Special Economic District, China suddenly arrested him on charges of bribery and tax evasion. Amidst the ensuing confusion, Pyongyang eventually canceled the creation of the Sinuiju Special Zone (Yonhap News, September 24, 2002). In response to the sinking of the South Korean corvette Cheonan by North Korea in 2010, the U.S. and South Korea planned military exercises in the Yellow Sea involving a U.S. aircraft carrier. China fervently objected to the presence of an American carrier in the Yellow sea, causing the Obama administration to move the exercises to the East Sea (also known as the Sea of Japan) (China.org.cn, July 7, 2010). Thus, the primary task of China’s North Sea Fleet , is to fully control the Yellow Sea in order to protect the approaches to Beijing.
The Yellow Sea region is also vitally important to China from an economic perspective. Western China is dominated by deserts and mountain ranges, whereas the eastern part is densely populated with many major cities, including Dalian, Qingdao, and Shanghai, which are all on the coast of the Yellow Sea and account for a very high percentage of the Chinese economy. In addition, there is an oil field in Bohai Bay, which lines in the innermost area of the Yellow Sea. Given its strategic and economic value to China, it is unsurprising that Beijing seeks to deny external powers, particularly the U.S., access to the Yellow Sea. However, China’s effort to essentially turn the Yellow Sea into its own domain is extremely worrisome for Seoul (Newsis, February 25, 2011). 
If China achieves its goals in the Yellow Sea, it will also considerably advance Beijing’s efforts to bring about unification with Taiwan. For China, achieving full control of the Yellow Sea is a prerequisite for a successful attack on Taiwan.  In order to achieve a forcible reunification, China will need to control the East China Sea to the north of Taiwan and the South China Sea to the south. Establishing control of the East China Sea will prove challenging, as Japan maintains substantial naval power there. In order to succeed in any struggle with Japan, China must secure the Yellow Sea to serve as a strong rear base for operations.
Furthermore, by blocking the Yellow Sea, China could also divide Japan’s naval forces. The Japanese fleet has two components, one in the Pacific and one in the East Sea (a.k.a. Sea of Japan), with the Japanese islands in between them. Passage from the East Sea to the East China Sea skirts the edge of the Yellow Sea, so China taking full control of the Yellow Sea would limit Japan’s ability to support the defense of Taiwan. Likewise, should China achieve total control of the Yellow Sea, this would also prevent U.S. Forces in Korea (USFK) in Pyeongtaek from being transported by ship from this port on the west coast of Korea. Again, this would hamper support for Taiwan.
China’s Current Actions in the Yellow Sea
The second issue that deserves greater attention is China’s current actions in the Yellow Sea.
From a security standpoint, China is, broadly speaking, seeking to strengthen its maritime dominance in the Yellow Sea through military power. Moreover, in economic terms, China is attempting to extract as many resources from the waters as possible. Since around 2010, China has sought to strengthen its North Sea Fleet, having previously prioritized its East Sea Fleet which focuses on Taiwan, and its South Sea Fleet, which contends directly with the U.S. Navy in a struggle to establish and secure maritime territories in the South China Sea. The North Sea Fleet was thus the place where the oldest ships were re-deployed, earning it the moniker “the Nursing Home Fleet.” Recently, however, the PLA Navy (PLAN) has been deploying newer ships to the North Sea Fleet, including both Type 055 destroyers and the latest Type 052D destroyers.  China enjoys overwhelming naval superiority over South Korea in the Yellow Sea, but the South Korean Navy nevertheless maintains a policy of responding proportionally to the PLAN. If the South Korean Navy sends one warship towards China, however, the PLAN sends five or six ships as a countermeasure, so the effectiveness of the South Korean Navy is limited by China’s quantitative advantage.
The economic importance of the Yellow Sea for China is underpinned by political motives, specifically the need to achieve economic stability in northeast China, and garner popular support for the ruling Communist Party. The provinces bordering the Yellow Sea are Shandong [山东] and Liaoning [辽宁], which along with Heilongjiang [黑龙江] and Jilin [吉林] comprise the Three Northeastern Provinces [东北三省, Dong Bei San Sheng]. Notably, the population of the Three Northeastern Provinces includes many ethnic Koreans and Manchurians and relatively fewer Han Chinese, so this region has historically presented a threat to Beijing. Thus, the region is considered to be more vulnerable to political disaffection than other regions; hence the importance of ensuring economic stability.
China has been passive about negotiating the delimitation of the maritime boundary, but it has engaged successfully with South Korea on fisheries, signing a 2001 Fisheries Agreement to create a Provisional Measures Zone managed by a Joint Fisheries Commission to manage overlapping exclusive economic zone (EEZ) use given the lack of maritime boundary delimitation.  While Chinese authorities punish illegal fishing in response to South Korean requests, they do not take the initiative to independently enforce the agreement. Fish stocks have been devastated by maritime pollution and overfishing, so China is also promoting fish farming in order to meet the economic needs of the regions adjacent to the Yellow Sea.
A Policy Challenge
Concerns are growing in South Korea that Beijing is ultimately seeking to turn the Yellow Sea into a Chinese inland sea and is therefore beginning to consider China as a potential military threat. In addition to the PLAN, the PLA Air Force also present concerns for South Korea. The South Korean Navy has daily encounters with Chinese vessels in the Yellow Sea, and the South Korean Air Force routinely monitors Chinese aircraft departing from the Yellow Sea, circling the southern part of the Korean Peninsula without giving notice of entering KADIZ (Korea Air Defense Identification Zone). There are also joint flight exercises between Chinese and Russian military aircraft in the East Sea (a.k.a. Sea of Japan). In July 2019, during one such exercise, a Russian military aircraft entered the territorial airspace of Dokdo, an island that is claimed by both South Korea and Japan in a longstanding dispute. During this incident, South Korean fighters fired warning shots. Due to increased military presence in the region, there is clearly a growing risk of a serious accidental military confrontation (Yonhap news, July 23, 2019).
From a South Korean perspective, it is also troubling that China’s efforts to assert control over the Yellow Sea have progressed largely undisturbed. China has had naval predominance in the Yellow Sea since 2010, when US carriers were withdrawn from its waters (Xinhua Daily Media Group, August 27, 2020). In recent years, the U.S. military has conducted reconnaissance flights to monitor Chinese military activity in the Yellow Sea. On August 25, 2020, USFK sent a U-2 reconnaissance aircraft over the Bohai Bay. The PLA had previously announced a no-fly zone from August 22-26 in the Yellow Sea and the Bohai Bay, and was conducting military exercises. A Chinese military spokesperson strongly condemned the US flight (Xinhuanet, August 26, 2020). U.S. efforts to counter China have been largely focused on the South China Sea and the Taiwan Strait. Meanwhile, South Korea, the country most closely affected by China’s Yellow Sea activities, has limited options to respond to China’s growing naval strength and assertiveness.
Unfortunately, external powers have demonstrated relatively little interest in the Yellow Sea. America is occupied by Chinese naval forces elsewhere in Northeast Asia, and so it seems that the Yellow Sea is destined to become a Chinese inland sea. On its own, South Korea can do little to prevent or even delay this outcome, but if and when China takes full control of the Yellow Sea, then the U.S. and Japan will surely regret their current inaction.
Joshua NT Park is a Ph.D. Senior Researcher in IAS (Institute for Asian Strategy), Seoul Korea. He is currently a visiting scholar in Taipei, Taiwan.
 Negotiations to establish the Korea-China Maritime boundary in the Yellow Sea have been ongoing since 1996 but without significant progress. South Korea insists on a median line equidistant from the two coastlines; whereas China argues that comparative length of relevant coastlines, the relative population of fishermen, and the topography of seabed should be considered, emphasizing “equity”. However, since the creation of a provisional measures zone by the Sino-Korean fisheries agreement signed in 2001, China has no major problems with fishing, and expects its negotiating position to improve as time goes on. China is therefore not actively pursuing the maritime boundary delimitation negotiations with South Korea.
 Usually, the term ‘inland sea’ refers to semi-enclosed oceanic areas completely surrounded by land or connected to the ocean on one side. The connotations of the term therefore imply that such waters are fully under Chinese jurisdiction. In South Korea, China’s attempt to gradually seize the Yellow Sea has raised significant concerns. The issue was discussed at the National Assembly in 2011 when National Assembly member Chung Mong-joon demanded measures in response from then Prime Minister Kim Hwang-shik.
 See Chinese scholar Zhang Wenmu’s book, which highlights the role of the Yellow Sea as part of the bigger picture of Taiwan’s unification, Zhang Wenmu [张文木], On Chinese Sea Power [论中国海权] (Beijing: Ocean Press), 2009.
 The Type 055 and Type 052D destroyers are the Chinese Navy’s most modern surface ships. In particular, the Type 055 Nanchang (南昌), launched on January 13, 2020, is the largest similar vessel in Asia (12,000 tonne-class) with Aegis-class air defense capabilities.
 See Young Kil Park, “The Role of Fishing Disputes in China–South Korea Relations,” National Bureau of Asian Research Maritime Awareness Project, April 23, 2020, https://www.nbr.org/publication/the-role-of-fishing-disputes-in-china-south-korea-relations/