Irony on the Yellow Sea: Contrasting North and South Korean Responses to Chinese Encroachment

The Yellow Sea, separating China from the Korean Peninsula, has long been a theater of economic competition, strategic maneuvering, and diplomatic tension. It was here that the stage was set for two dramatic incidents that, when viewed side by side, reveal a telling contradiction in Northeast Asian geopolitics. North Korea, China’s historically, resorted to lethal violence against Chinese fishermen accused of illegal fishing. Meanwhile, South Korea, a close U.S. ally and frequent target of Chinese strategic pressure, responded to the erection of Chinese marine structures in contested waters with legal restraint choosing instead to pursue an amicable resolution through diplomatic channels. While this juxtaposition upends conventional expectations about alliances and rivalries, it also exposes the conflicting realities that underpin the region’s security landscape.

Rising Tensions in the Yellow Sea

The Yellow Sea is far more than a geographical boundary. Its waters are rich with fisheries, undersea oil and gas reserves, and serve as a vital shipping lane for Northeast Asia’s economic powerhouses. These rich waters, however, come with complications: the exclusive economic zones (EEZs) of China and South Korea overlap, creating a Provisional Measures Zone (PMZ) governed by a 2001 fisheries agreement that is, at best, ambiguously worded and loosely enforced.

In recent years, China has begun deploying massive steel structures—ostensibly for salmon aquaculture—within the PMZ. These installations, such as the Shen Lan 2 Hao underwater cage supported by its own jack-up rig, are symbols of China’s growing maritime assertiveness. The existence of these structures was confirmed through exclusive satellite imagery first obtained by Ray Powell at the Stanford University-affiliated maritime transparency initiative SeaLight. South Korean officials and experts suspect that these “fish farms” may serve dual purposes, strengthening China’s territorial claims and potentially restricting access to other states.

South Korea’s Response to China: Restraint and Diplomacy

On February 26th 2025, a South Korean research vessel, the R/V Onnuri, escorted by the South Korea Coast Guard, approached the Chinese Shen Lan 2 Hao installation in the PMZ. Citing rights under the 2001 Korea-China Fisheries Agreement, the South Korean team sought to inspect the structure and its nearby rig. The Chinese response was swift: coast guard ships and civilian-crewed boats intercepted the Koreans, leading to a tense two-hour standoff. Some Chinese civilians reportedly brandished knives and demanded the South Koreans leave.

Faced with this challenge, South Korea chose the path of restraint. Instead of defaulting to the use of force, Seoul lodged formal diplomatic protests and publicized the incident. The government deployed its own floating platform in the area earlier in the year to conduct environmental surveys and monitor Chinese activities—a clear signal of resolve, but one that stopped short of confrontation. Domestically, some voices called for sanctions against Chinese firms involved with the installations, but cool heads prevailed—no doubt tempered by the reality of South Korea’s deep economic ties to China.

Instead of saber-rattling, South Korea leaned on legal and diplomatic tools. It invoked the fisheries agreement and demanded bilateral talks. This approach reflected not only a desire to avoid escalation but also reinforced South Korea’s international image as a responsible actor committed to the rule of law.

North Korea’s Response to China: Escalation and Violence

In the August of 2020, a deadly incident underscored the risks faced by Chinese fishermen allegedly engaged in illegal, unreported, and unregulated (IUU) fishing in North Korean waters. On August 11, a North Korean patrol boat opened fire with live rounds on a Chinese vessel near Haeju and Ongjin County in South Hwanghae Province, off North Korea’s west coast. The Chinese boat was part of a group of about ten vessels fishing illegally in the area. Three Chinese fishermen were killed in the incident.

This marked a significant escalation from previous years, when North Korean patrols typically relied on threats or warning shots—often as a means to extract bribes from Chinese crews. After the shooting, the damaged Chinese vessel was towed away by other boats in the fleet, and Chinese authorities reportedly worked to suppress news of the incident and temporarily banned fishing in sensitive border areas like Dandong.

Additionally, in June 2020, another disturbing case was reported: an empty Chinese fishing boat was found near Dandong with bloodstained footprints and a piece of human ear on board. Chinese authorities concluded that the North Korean coast guard was likely responsible, but the case was quietly set aside without further action.

As the years passed, North Korean maritime patrols further escalated their enforcement actions. A particularly alarming case involved two Chinese fishing boats operating in North Korean waters in mid-October 2024. According to a source cited by Daily NK, a North Korean patrol vessel pursued one of the boats, opened fire, and the targeted vessel “never returned and disappeared.” The source stated, “The boat had a crew of two, and since they didn’t return after the gunfire, they were probably hit and killed. Such things have happened a lot recently”.

These disappearances are not isolated. As North Korean patrols intensify their crackdowns, reports of vessels vanishing after encounters with North Korean authorities have increased. Chinese owners, often operating with unlicensed crews to avoid state insurance costs, sometimes fail to report such incidents, further obscuring the true scale of the problem.

The Irony Unpacked

Herein lies the central irony: North Korea, China’s supposed ally, responded to Chinese maritime encroachment with deadly violence. South Korea, China’s perceived competitor, responded to similar Chinese actions with restraint and due process.

This transposition of expected behavior challenges several assumptions regarding how alliances and rivalries shape state conduct. One might expect that North Korea, reliant on Chinese economic and diplomatic support, would avoid antagonizing Beijing. Conversely, South Korea, often at odds with China over security issues, might be more confrontational.

Why the stark difference? For North Korea, sovereignty over its waters is a matter of regime survival and internal legitimacy. The Kim regime has little to lose diplomatically and much to gain by signaling toughness to both domestic and foreign audiences. Its willingness to use violence—even against its primary benefactor—underscores the utilitarian nature of the China-North Korea relationship.

South Korea, on the other hand, is constrained by its democratic institutions, international image, and economic integration with the rest of the world. Escalation could jeopardize trade, alienate allies, or trigger broader conflict. Seoul’s preference for diplomatic tools reflects both prudence and the balancing of national interests in addition to regional stability.

Implications for Regional Security and Governance

These contrasting responses have brought with them important lessons for the future of maritime security in Northeast Asia. The risk of escalation is ever-present, especially as ambiguous legal frameworks and “gray zone” tactics become more prevalent. China’s use of IUU fishing, unidentified rigs, civilian militia, and coast guard assets to assert control creates tension in the region. North Korea’s response, the disproportionate use of force, only adds to this tension. Meanwhile, South Korea’s cautious balancing act seeks to manage these pressures—but looks to be increasingly untenable given recent escalations.

The incidents highlight the urgent need for new regional mechanisms to manage disputes. Recommendations from policy experts include establishing joint patrols and real-time monitoring among China, North Korea, and South Korea—ideally under a neutral multilateral body. Enhanced transparency, independent investigations of incidents involving loss of life, and the enforcement of international labor standards on fishing vessels are also efforts deserving of consideration. Without such reforms, the cycle of illegality and impunity is likely to continue—with potentially devastating consequences for the Yellow Sea’s prized marine resources.