Seoul reaffirms its maritime claims after a tense standoff with Chinese vessels over a new steel structure in contested Yellow Sea waters.
On Tuesday, the South Korean foreign ministry confirmed reports of a recent clash between its and Chinese coast guards in a disputed maritime region of the Yellow Sea. The two-hour standoff last month was first reported on March 18 by the Chosun Daily. “The Korean government has actively responded at the government level to ensure our legitimate and legal maritime rights in the Yellow Sea are not affected,” foreign ministry spokesperson Lee Jae-woong said during the agency’s daily briefing. “We have also conveyed our firm position to the Chinese side regarding the reported incident.”
He added that through active measures, Seoul would continue to protect its rights in the contested zone. The ministry had also summoned Chinese Embassy officials to protest.
The foreign ministry did not give details, but did not dispute the version of events in media reports that cited unnamed officials. According to those reports, last month’s confrontation occurred when South Korea dispatched its research vessel Onnuri to investigate a Chinese-built structure in a disputed area.
About one kilometer (0.6 miles) from the structure, a Chinese coast guard vessel and three inflatable boats—operated by non-uniformed Chinese personnel—blocked the survey.
The South Korean Coast Guard responded by sending its own ship, resulting in a two-hour standoff.
China insisted the facility was part of an aquaculture farm and demanded the South Korean vessel leave, while Seoul maintained its right to conduct the survey. Some non-uniformed Chinese reportedly carried knives, though they did not use them.
The standoff ended without violence but the investigation was halted due to Chinese opposition.
When asked about the standoff on March 18, Chinese foreign ministry spokesperson Mao Ning said she wasn’t familiar with the specifics but
called the situation at the Yellow Sea “stable.” She also said the two countries “maintained sound communication” over maritime affairs.
This incident is part of ongoing tensions between South Korea and China over maritime sovereignty in the Yellow Sea. In the past year, China has repeatedly
installed large structures in the disputed area without South Korea’s permission.
In December, South Korean intelligence agencies
discovered another steel structure—about 50 meters (164 feet) wide and more than 50 meters tall—had been moved into what is formally known as the “Provisional Measures Zone” (PMZ), where South Korean and Chinese Exclusive Economic Zones (EEZs) overlap. An EEZ is a 200-nautical-mile zone where a country has special rights to explore and use marine resources. Since South Korea and China are less than 400 nautical miles apart, their EEZs overlap, and official boundaries remain unresolved.
China had previously installed similar facilities in April and May 2024 but later
removed them after protests from Seoul. Beijing calls them “fishing support facilities.”
Under a 2001 agreement, neither side may erect structures or exploit sub-seabed resources in the PMZ, except for fishing.
China’s activities go beyond the installation of structures. A 2020 South Korean Ministry of National Defense report
noted that Chinese military ships crossed into areas under South Korea’s jurisdiction more than 900 times between 2016 and 2020, with such incursions rising after Seoul deployed the THAAD (Terminal High Altitude Area Defense) system in 2017, local media reported.
THAAD is a U.S.-designed and manufactured anti-missile system installed in South Korea between 2016 and 2017 as a bulwark against a potential North Korean missile attack.
But Beijing has insisted that the deployment of THAAD affects China’s security and has since adopted a series of countermeasures and boycotts against South Korea.
This maritime dispute unfolds amid political uncertainty in South Korea. President Yoon Suk Yeol, known for his pro-U.S. and Japan-friendly stance while distancing the country from socialist China and North Korea, faces an ongoing impeachment process initiated in December 2024. The move came after Yoon imposed martial law,
citing the opposition’s efforts to gridlock the nation’s unicameral National Assembly and controversies surrounding the National Election Commission.
The maritime boundary in the Yellow Sea remains undefined. In 2013, China unilaterally
proclaimed the 124°E meridian as a dividing line and forbade the South Korean Navy from crossing it—an assertion Seoul rejects because it would give China control of more than 70 percent of the Yellow Sea.
Beijing has pursued similar tactics in the South China Sea, where it built artificial islands on disputed reefs and declared them part of its territorial waters, sparking sovereignty disputes with several countries.
