China has been following a sustained strategy of frequent unannounced incursions into the Exclusive Economic Zone of countries with whom it has contested claims over international waters.
After perfecting the ‘Gray Zone’ tactics in the South China Sea, the Chinese warships are militarising the Yellow Sea to bolster their claims on the international water body it shares with South Korea.
As per a South Korean English Daily in 2024, Chinese warships crossed into South Korea’s Exclusive Economic Zone (EEZ) over 330 times.
The military data obtained by the newspaper indicate that the incursions were not limited to the Provisional Measure Zone (PMZ) in the Yellow Sea, where the Exclusive Economic Zones (EEZs) of the two countries overlap, but also extended into areas that are part of South Korea’s EEZ.
The Yellow Sea is a semi-enclosed sea bounded by the Chinese mainland on the west, the Korean Peninsula on the east, and a line running from the mouth of the Yangtze River to the south side of Cheju Island.
It has geostrategic and military significance for China. It has a long history of contestations, conflicting historical narratives, and sovereignty claims. The control of the Yellow Sea has been central to Japan’s strategy during the Russo-Japanese War.
Since the establishment of the People’s Republic of China, Beijing has viewed the Yellow Sea as a strategic corridor connecting the Bohai Gulf to its capital. China has fortified its islands and expanded its coast guard and maritime militia presence, exerting pressure on both Koreas.
The contest would impact many powers as China’s nuclear submarine base is located in the Yellow Sea. It is also home to the South Korean Navy’s Second Fleet and the US military’s Camp Humphreys.
Overfishing and conflicting claims led to the establishment of the PMZ under a 2000 agreement, which allows fishing and navigation in the disputed region until the maritime boundary issue is resolved.
This differs from the EEZ, which extends 200 nautical miles from the coast and grants the claimant country exclusive rights to access its underwater resources and fishing grounds, as per international maritime law.
The Chosun Daily reported: “The frequent crossings appear to reflect China’s broader strategy of turning the Yellow Sea into what it sees as an inner maritime zone, expanding its activities in South Korean waters as part of that effort, including the construction of permanent offshore structures.”
As the EurAsian Times earlier reported, China has been increasing its presence in the Yellow Sea, following the construction of a massive steel rig.
The Coast Guards of the two countries recently had a two-hour-long standoff after Korean ships wanted to investigate the steel structure. The confrontation took place on the afternoon of February 26 in the PMZ near Socotra Rock, southwest of South Korea’s Jeju Island.
Shen Lan 2 Hao (or Deep Blue 2) is a 71.5-meter-tall underwater marine cage deployed by China into the PMZ for salmon aquaculture. The massive cage and the jack-up support rig sparked concern in South Korea. The Korean government asserts its right to inspect the structure under the 2001 Korea-China Fisheries Agreement.
The absence of a maritime boundary in the narrow Yellow Sea, where the opposite coasts are less than 400 nautical miles (nm) apart, has been a cause of maritime disputes between China and South Korea.
The military documents indicate that, while the number of times Chinese warships entered the South Korean Exclusive Economic Zone (EEZ) was 330 in 2024, by mid-April of 2025, the number had already surpassed 100.
EEZs extend 200 nautical miles from the coast and grant the claimant country exclusive rights to access its underwater resources and fishing grounds, as per international maritime law.
While EEZs are technically international waters under the law of the sea, foreign military vessels operating within them are subject to the host country’s surveillance. None of the Chinese warships entered the territorial waters of South Korea, which would have constituted a breach of the country’s maritime sovereignty.
The number of Chinese naval crossings has increased sharply over the past several years.
In 2017, there were about 110 such entries, but the figure more than doubled to 230 in 2018 as US-China tensions escalated and concerns over Taiwan grew. The number climbed to 290 in 2019, stayed at roughly 200 per year through 2022, and then surged to 360 in 2023.
One incident stands out in particular. In 2020, a Chinese patrol ship crossed the 124th Meridian and approached within about 40 kilometers of Baengnyeong Island. The South Korean Navy had to dispatch a warship to force the vessel away.
According to the South Korean military officials, Beijing sees the Yellow Sea as not only a “strategic theatre” for emergencies involving the Korean Peninsula but also when a crisis erupts in the Taiwan Strait.
A Passage For Chinese Nuclear Submarines
China has several important naval bases closer to the Yellow Sea. Most recently, satellite imagery revealed a previously hidden Chinese military base where six nuclear submarines were resting. The First Submarine Base in Qingdao has direct access to the East China Sea, the Yellow Sea, and the Sea of Japan.
The submarines in Qingdao included Type 091, Type 093A, and Type 094 ballistic missile submarines, and the base is critical for China’s maritime operations. In fact, submarines from this base were found to be operating in South Korea’s EEZ.
China’s Lianyungang Naval Base, located further south, supports surface warships and amphibious operations of the PLA Navy. It plays an important role in monitoring regional maritime activities and securing China’s coastline.
Yantai and Dalian Naval Facilities in the region are used for coast guard operations and naval logistics. They help enforce China’s maritime claims and patrol disputed waters.
Due to these military assets, China has been pressuring the South Korean Navy to cease operations west of the 124th Meridian.
The 124th meridian east is a line of longitude that has been informally used as a maritime boundary between China and South Korea in the Yellow Sea. While it has no legal recognition under international law, China has increasingly asserted control over waters near this line, leading to tensions with South Korea.
China claims the 124th meridian as part of its territorial waters, citing a 1962 border treaty, but South Korea considers it part of its exclusive economic zone (EEZ).
Choi Yun-hee, a former chairman of the Joint Chiefs of Staff, was quoted by the South Korean media as saying that China had made a similar demand during his 2013 visit when he was the chief of naval operations. He opined that China treats the Yellow Sea as its own inner waters and structures like Shenlan-1 and Shenlan-2, if left “unchecked”, could lead to the area falling under Beijing’s control.
