What’s below the surface of the Korea–China tensions over steel platforms in the Yellow Sea?

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What’s below the surface of the Korea–China tensions over steel platforms in the Yellow Sea?

Published: 29 Apr. 2025, 18:34 Updated: 30 Apr. 2025, 11:25

SEO JI-EUN
[email protected]

Audio report: written by reporters, read by AI

The third Korea-China Maritime Cooperation Dialogue takes place in Seoul on April 23, where the two sides discussed China's unilateral installation of steel structures in the Yellow Sea’s Provisional Measures Zone, an area where their 200-nautical-mile exclusive economic zones (EEZs) overlap. [MINISTRY OF FOREIGN AFFAIRS]

[EXPLAINER]

Korea and China are in a dispute over steel structures Beijing installed in a contested area of the Yellow Sea, with Seoul formally requesting their relocation outside the designated zone where only fishing activities are permitted.

China, in response, reiterated that the structures are aquaculture facilities unrelated to sovereignty, but indicated it would be willing to arrange an on-site visit for Korean officials if requested.

While Beijing stopped short of agreeing to remove the structures, it reportedly conveyed informally that it would not install additional facilities — at least for now — during the recent exchange, amid rising bipartisan criticism in Korea.

Security experts warn, however, that the installations could mark the beginning of a campaign by China to expand its maritime influence in the Indo-Pacific region through "gray zone" tactics, exploiting regional uncertainty and testing Seoul’s response.

Images of Chinese steel structures unilaterally installed in the Korea-China Provisional Measures Zone (PMZ) of the Yellow Sea, obtained and revealed by Rep. Um Tae-young of the People Power Party on April 24. From left: Shenlan 1 (installed in 2018), Shenlan 2 (2024) and a management facility built in the form of an oil drilling platform (2022). [YONHAP]

What's the dispute about?

The dispute centers on the Korea-China Provisional Measures Zone (PMZ), an area where the two countries' exclusive economic zones (EEZs) overlap and where negotiations to establish a formal maritime boundary are still ongoing.

An EEZ extends up to 200 nautical miles (about 230 miles) from a country’s coastline, granting it exclusive rights to explore and exploit natural resources under international maritime law.

China claims the 124th meridian east as the demarcation line for its territorial waters in the Yellow Sea — referred to as the West Sea in Korea — citing a 1962 border treaty. This line falls inside the area that Korea considers part of its EEZ.

Chinese steel structures in the Yellow Sea [YUN YOUNG]

To manage the disputed area, the two countries signed the Korea-China Fisheries Agreement in 2001, establishing the PMZ where both sides would conduct joint fishing activities and co-manage fishery resources and agreed to avoid unilateral actions beyond fishing operations to prevent prejudicing the eventual boundary settlement.

It only came to light in March that China installed three large steel structures — described as salmon aquaculture platforms and management facilities — near the western edge of the PMZ.

Tensions escalated on Feb. 26 when a Korean ocean survey vessel attempted an on-site investigation, only to be forcibly blocked by Chinese coast guard ships and civilian vessels — leading to a two-hour standoff that required the deployment of Korean Coast Guard patrol ships.

Kang Young-shin, director-general of Northeast and Central Asian Affairs Bureau at the Ministry of Foreign Affairs, left, and Hong Liang, director-general of the Department of Boundary and Ocean Affairs at China's Ministry of Foreign Affairs, pose for a photo at the third Korea-China maritime dialogue held in Seoul on April 23. [MINISTRY OF FOREIGN AFFAIRS]

What was Korea's response?

Korea and China held the third Korea-China Maritime Affairs Dialogue and Cooperation Mechanism — a director-general-level talks on maritime affairs — on April 23 in Seoul, primarily discussing China’s unilateral installation of steel structures in the Korea-China PMZ.

It was the first in-person meeting, after the previous sessions were held virtually since 2021.

During the talks, Kang Young-shin, director-general of Northeast and Central Asian Affairs Bureau at the Ministry of Foreign Affairs and Seoul’s chief delegate, conveyed Korea’s "deep concern," emphasizing that the country's "legitimate and lawful maritime rights must not be infringed."

He also warned that if China claims relocation of the structures is difficult, Korea may have to consider "proportional countermeasures."

Korean Foreign Minister Cho Tae-yul further indicated during a parliamentary questioning session on Monday that the government is reviewing a range of possible responses — including the installation of a marine science research base — as part of its proportional responses.

“We will determine specific actions through a comprehensive review of factors such as the Chinese side’s future behavior and the economic feasibility of our options,” Foreign Ministry spokesperson Lee Jae-woong said during a press briefing Tuesday.

The day after the maritime talks, Korea’s National Assembly Agriculture, Food, Rural Affairs, Oceans and Fisheries Committee approved a 60.5 billion won ($41.9 million) budget to counter China’s unauthorized construction activities in the PMZ. If passed by the plenary session, the funds could be used to install structures in the zone.

Shenlan 1 installed by China in the Korea-China Provisional Measures Zone (PMZ) of the Yellow Sea [YONHAP]

What does China claim?

China, however, has maintained that there is no violation.

At the meeting, Hong Liang, director-general of the Department of Boundary and Ocean Affairs at China's Ministry of Foreign Affairs and Beijing’s chief delegate, reiterated that the installations are "purely aquaculture facilities" and unrelated to sovereignty or maritime boundary claims, a senior Foreign Ministry official told reporters on Thursday following the meeting.

According to a Seoul source, China explained that two of the platforms — Shenlan 1 and 2 — are floating aquaculture facilities, while the third structure, which resembles an oil drilling platform, is not permanently fixed to the seabed. By emphasizing the non-permanent nature of the installations, China appeared to suggest that their activities do not violate the United Nations Convention on the Law of the Sea (Unclos), which prohibits actions that cause permanent physical changes in undelimited maritime zones.

China reportedly expressed reluctance to relocate the structures, citing that they are private investments into aquaculture facilities.

Shenlan 2 installed by China in the Korea-China Provisional Measures Zone (PMZ) of the Yellow Sea [YONHAP]

Shenlan 1, installed in 2018, and 2, installed in 2024, are used for farming cold-water fish such as salmon and trout in deep-sea environments, while the drilling rig-like platform, installed in 2022, is said to function as a support facility for storing feed and managing the aquaculture platforms.

China also offered to allow Korean officials to conduct an on-site inspection if requested, the source said.

However, whether such an inspection will materialize remains uncertain.

Korean officials are concerned that sending an inspection team could be interpreted as tacit acceptance of the structures’ legitimacy.

The Korean Foreign Ministry official said the government is "carefully reviewing how to address the concerns before proceeding" with any inspection plans, signaling a cautious approach.

What is China's next move?

Korean officials believe that China is unlikely to proceed with additional installations of steel structures in the Yellow Sea, as both sides agreed on the need to prevent the dispute from undermining bilateral relations. Media reports were claiming China may expand up to 12 such structures.

A Korean Foreign Ministry official told reporters Thursday that the two sides shared the view that the Yellow Sea structures issue should not become an obstacle to the overall development of Korea-China ties, especially with Chinese President Xi Jinping's potential visit to Korea later this year for the Asia-Pacific Economic Cooperation (APEC) summit in Gyeongju.

"China often cancels meetings at the last minute when uncomfortable situations arise, but in this case, they showed a willingness to communicate," the official said.

Both sides agreed to maintain communication through all available diplomatic channels, the official added.

The next round of maritime cooperation talks is expected to be held in China.

China's Ministry of Foreign Affairs issued only a brief statement following the talks, saying that the two sides "had an exchange of views on fishery aquaculture in the Southern Yellow Sea" without disclosing specific details.

The Chinese coast guard lands on the disputed Tiexian Reef — known as Sandy Cay in the Philippines — in the South China Sea and raises the Chinese flag to assert sovereignty and jurisdiction, according to a report by China’s state-run Global Times on April 24. [SCREEN CAPTURE]

What sort of strategy is at play?

Security experts warn that China’s activities may reflect a familiar "gray zone" strategy — using non-military means to gradually change the status quo without open conflict.

Victor Cha, Korea Chair at the Center for Strategic and International Studies (CSIS), noted that China may be seeing opportunity "at a time of great uncertainty."

“There’s a lot of disorder in the world today, and most countries are pessimistic about it. But there are a few countries that are optimistic about the disorder — and one of them is China — because they see advantage to a distracted United States, to a tariff war, to a lot of the uncertainty in the world today," Cha said during a press roundtable hosted by the Asan Institute on the sidelines of the Asan Plenum in Seoul on April 23.

The use of indirect pressure tactics, including maritime actions and economic coercion, is nothing new, he added.

Victor Cha, Korea chair at the Washington-based think tank Center for Strategic and International Studies, speaks during a press roundtable hosted by the Asan Institute on the sidelines of the Asan Plenum in Seoul on April 23. [ASAN INSTITUTE FOR POLICY STUDIES]

He pointed to China’s backlash over the deployment of the U.S.-led Terminal High Altitude Area Defense (Thaad) system to Korea in 2017 and “potential critical minerals cut-off to Korea for chip exports to the United States” as “examples of economic coercion that China has used quite frequently for decades" against countries in the Indo-Pacific.

Randall Schriver, former U.S. assistant secretary of defense for Indo-Pacific security affairs under President Donald Trump's first term and current chairman of the Virginia-based think tank Project 2049 Institute, similarly warned against underestimating the strategic significance of China's actions at sea, citing past behavior in the South China Sea.

China has created artificial islands in the South China Sea by reclaiming several reefs, leading to territorial disputes with neighboring countries such as the Philippines and Vietnam. While the structures initially appeared to serve as lighthouses or fishing support facilities, they were gradually transformed into military outposts equipped with missile systems and radar installations, effectively restricting the movement of nearby vessels and aircraft.

“What we learned is it's not about the feature itself; it's about the surrounding maritime areas," Schriver said. "We shouldn't minimize a small project to create a feature from a low tide elevation. It's about broader ambitions."

"If China proceeds, it would be something we would have to monitor very closely, have very active reconnaissance activities, and use diplomatic channels to protest the destabilizing nature of these activities," he added. "We don't want to see the same pattern repeated in other areas."

What do other countries say?

The United States and Japan also weighed in on China's maritime activities in the Yellow Sea.

"China's decades-long refusal to abide by international law, including freedom of navigation, hampers its own economic interests and causes instability in the region," a U.S. State Department spokesperson said in response to media inquiry last week. This is the first time the State Department addressed the recent tensions in the Yellow Sea.

Japan’s Yomiuri Shimbun similarly reported in its coverage of the third Seoul-Beijing maritime talks that China’s unilateral installation of structures in the PMZ could be an attempt to alter the status quo, possibly paving the way for future jurisdictional claims.

The newspaper pointed out that building structures at sea to assert maritime rights has been a familiar tactic for China, citing past examples such as the construction of artificial islands and airstrips in the South China Sea and the installation of structures and buoys related to gas fields in the East China Sea.

BY SEO JI-EUN [[email protected]]