On December 31, 2015 China began a major overhaul of its structure military organizational structure. This included the abolition of the seven previous Military Regions (军区) and the creation of five Theater Commands (战区) (See China Brief, February 4 and February 23). Many units previously under one Military Region have found themselves under a new command. The Southern Theater Command (STC) is one such structure, composed of parts of the former Chengdu and Guangzhou Military Regions. Covering an area almost double the size of Texas and a population (320 million) larger than that of the entire United States (318 million), the Southern Theater Command is responsible for China’s important borders with Myanmar and Vietnam and the vast area claimed by China in the South China Sea. 
The South is one of China’s most important strategic directions (战略方向), as it is a major source of trade, fish resources, and potentially oil, gas and hydrate deposits. Two of China’s strongest economies, Guangdong Province and Hong Kong, sit at the center of the Theater Command. Xi Jinping visited the area shortly after becoming Chairman of the Central Military Commission (Beijing News, December 13, 2012; Gov.cn, December 12, 2012). In an interview, the STC’s commander, General Wang Jiaocheng (王教成), described the STC as “guarding the motherland’s Southern gate” and as having “shouldered the important mission of protecting [China’s] interests in the South China Sea” (Xinhua, February 29). Particularly in the aftermath of the ruling by the Permanent Court of Arbitration (PCA) on China’s territorial claims in the South China Sea, the STC, the organization directly responsible for enforcing China’s claims of sovereignty, demands closer scrutiny. This brief overview and the accompanying map are an attempt to highlight the key features of this important organization within the PLA.
The Army, Navy and Air Force Theater Command Headquarters report to the Southern Theater Command. General Wang has also noted that one of the purposes of the Theater Commands is to improve the coordination between military services (Army, Navy, Air, and Rocket Forces) (Xinhua, February 29). The Southern Theater command, as home to an extensive land border, lengthy coastline (and larger maritime claims) and complex airspace, embodies the importance and difficulty of coordinating these disparate arms of China’s military. A brief description of each of the major services follows, highlighting the Southern Theater Commands’ essential units and equipment.
STC PLA Ground Forces are commanded by Liu Xiaowu (刘小午). Bai Lü (白吕) serves as commissar (The Paper, February 5). The Ground Forces include three Group Armies: 14th, 41st and 42nd. Reporting on military exercises in the region involving the 14th Group Army based in Kunming, Yunnan, indicates that its constituent brigades include a wide range of equipment and units, ranging from towed artillery to Type 96 tanks. Yunnan and Guangxi both share a border with Vietnam. Yunnan’s geography is particularly mountainous, posing significant problems for deployment. With the apparent calm in Myanmar’s internal conflict in the Kokang region that borders Southwestern Yunnan, stemming the cross-border flow of drugs and counter-terrorism will be the main priority for the areas’ security units. Despite past enmity and occasional tensions over maritime borders, the two sides have a number of established joint patrols and exercises. In late July, for example, Chinese police and border units practiced counter-terror operations with their Vietnamese counterparts (ChinaNews, July 29). Given China’s plans to further link its provinces to markets in Southeast Asia and along the Indian Ocean via Yunnan, this formerly sleepy corner of China may eventually become a more important transport corridor, raising the importance of PLA units stationed there.
Guangxi province is more densely populated than Yunnan and has an important rail-link between China and Vietnam. During 1979 this border saw the brunt of fighting during China’s brief war with Vietnam and subsequent skirmishes for several years afterward. The 41st and 42nd Group Armies, based in Guangxi and Guangdong respectively, are home to a number of large formations, including the 123rd Mechanized Infantry Division in Guigang, Guangxi, the 124th Amphibious Mechanized Division in Boluo, Guangdong and 163rd Infantry Division in Chaozhou, Guangdong.
Guangdong is by far the most densely populated of the provinces included in the STC, with a population of over a 107 million, not including Hong Kong and Macau. An Army Aviation brigade in Guangdong province has received China’s indigenous Z-10 and Z-19 attack helicopters (Youtube, August 30, 2013; China Military Online, January 11). Hainan province hosts the fewest ground troops, though the 132nd Infantry Brigade is based in Wuzhishan.
The Chinese Navy has emphasized the South as an important strategic direction since at least the early 1980s. In 1983 the Navy began training missions to the Spratly Islands.  PLA Navy Commander Liu Huaqing (刘华清), a long-time advocate of improving maritime power projection throughout the South China Sea, visited Woody Island (永兴岛) in 1987 to oversee the construction of a naval monitoring station (Party History Review, April 8). As home to one of China’s three fleets (North, East and South), and the primary base for its nuclear missile-equipped submarine force (Type 094 SSBNs) outside Sanya, Hainan, the South Sea Fleet (南海舰队) forms an important leg of China’s nuclear and conventional maritime deterrent.
The South Sea Fleet is currently commanded by Shen Jinlong (沈金龙) with Liu Mingli (刘明利) serving as commissar. Noteworthy units include the 2nd and 9th Destroyer Zhidui, located in Zhanjiang, Guangdong and Sanya, Hainan respectively. Hainan is also home to a coastal defense battery which appears in satellite imagery to be stationed outside Sanya, protecting the naval facilities there. The importance of the South Sea Fleet is further emphasized by the number of commissionings of advanced destroyers (and long range supply vessels). Military vessels are further backed up by a large number of Coast Guard and other maritime enforcement ships, many of which are recently decommissioned and repainted PLAN ships (China Brief, May 15, 2015).
The PLA Navy’s South Fleet continues to receive a higher proportion of advanced warships such as the Type 052D guided missile destroyer Yinchuan (银川) (China Military Online, July 12). Along with the deployment of land-based Surface Air Missile batteries such as the HQ-9 battery recently rotated out from Woody Island, these destroyers—including other members of the 9th Destroyer Zhidui outside Sanya—are improving China’s coastal air defense (China Brief, March 28). A large number of new long-distance supply ships (including most recently the Honghu and Luomahu) have also been commissioned into the South Sea Fleet, building up the logistic backbone needed to sustain operations far from shore (China Navy Online, July 15). The South Sea Fleet is also home to China’s two Marine Brigades (the 1st and 164th) (see also China Brief, December 3, 2010). The Marine Force was initially set up to provide the PLA with a dedicated amphibious force to take Bach Long Vi Island and other islands disputed between it and Vietnam.  These forces would be carried into combat by elements of the 6th Landing Zhidui, which includes the large amphibious landing ships such as the Jinggangshan (井冈山).
PLA Naval Aviation
The South Sea Fleet’s PLA Naval Aviation (PLANAF) 8th and 9th Divisions include a mix of legacy fighter aircraft as well as upgraded and indigenously produced variants such the J-11B and H-6K bombers. Their primary role is to defend China’s maritime airspace and, in the case of conflict, use a number of long-range anti-ship weapons such as the YJ-10 and YJ-100 that can be launched by JH-7B fighter-bombers from Hainan or H-6Ks strategic bombers flying out of Guiping-Mengshu Air Base in Guangxi (ChinaMil, February 4).
PLANAF elements of the South Sea Fleet have had a prominent role in challenging U.S. military electronic and maritime surveillance flights in international airspace near China’s coast and reclaimed islands. In 2001, a PLANAF J-8 fighter from the flying out of Lingshui Air Base on Hainan collided with an EP-3, forcing it to land at Lingsui AB. In August 2014, a J-11 fighter flying from Jialaishi AB, also on Hainan, performed a barrel roll over a P-8 aircraft.
PLA Air Force Theater (PLAAF) Commander Xu Anxiang (徐安祥) was promoted to the Southern Theater Command Deputy on July 25 (The Paper, July 26). An Zhaoqing (安兆庆) serves as political commissar. The Southern Air Force Theater commands a number of large units equipped with Su-27, J-11 and J-10 fighter jets, as well as older models such as the Mig-21 derived J-7. In 2015 The PLAAF deployed J-7s closer to the border with Myanmar after violence between government and (China Brief, July 17, 2015). These will likely be phased out as additional J-10s become available.
Chinese TV and print media released photos on July 18th showing an H-6K bomber flying over Scarborough Shoal (黄岩岛) (Sina, July 18). An accompanying statement trumpeted the PLAAF’s ability to conduct long range strikes and patrols. Though not confirmed by the reports, the bombers’ identification numbers appear to indicate that it belongs to the 8th Bomber Division, 24th Air Regiment of Leiyang, Hunan (See map). Other bombers of the same variant belonging to the PLANAF have conducted similar long distance patrols, through international air space in the East China Sea to the east of Okinawa. In the 1980s, during a period of similar unrest over territorial claims, earlier variants of the H-6 bomber belonging to Chinese Naval Aviation flew to Swallow Reef and Northeast Cay, making a similar statement. 
The 8th Bomber Division also operates some of China’s small fleet of aerial refueling tanker aircraft. This latter capability currently forms an important bottleneck to improving the capability of the Chinese Air Force and may be resolved as China brings its Y-20 strategic transport aircraft, or other airframes that could be converted to tankers, online.
The Rocket Force (formerly 2nd Artillery) also has bases and a number of launch brigades located within the borders of the Southern Theater Command. Though the Rocket Force, which is not examined here, reports to the Central Military Commission, they would no doubt play a role in Theater-level campaigns. 
Although the Southern Theater Command has yet to complete its reorganization of constituent units and needs to further improve communications between the services it commands, the fact of its creation is a clear sign of China’s commitment to streamline and upgrade its military forces. As units refine training and receive upgraded equipment, China’s ability to project power and deter along its strategic Southern axis will surely see a marked improvement.
Data is from China Bureau of Statistics 2014 and includes Hong Kong and Macau.
[Declassified] CIA-RDP84S00928R0003000050006-0, National Archive CIA Records Search Tool (CREST), China: Military Options Against Vietnam p. 10. The first training mission to the Spratly Islands occurred in May 1983.
CREST, pg. 11
These include launch brigades equipped with DF-21 C/D Anti-ship Ballistic Missiles (ASBMs) and CJ-10 ground-launched cruise missiles (GLCMs) that have ranges of 1,500km. Annual Report to Congress on the Military and Security Developments Involving the People’s Republic of China 2016, DOD, April 26, 2016. Pg. 25