South Korea should increase efforts to prevent China from normalizing its claims to sovereignty over a disputed maritime area in waters the two countries share, analysts say.

China has been doing it for decades in the South China Sea, analysts say, where it has been using so-called gray zone tactics to assert its claims over vast stretches of maritime territory — claims contested by several neighboring countries in the area.

Recent Chinese activity in the waters it shares with South Korea has prompted analysts’ warnings that Beijing is doing the same to Seoul.

South Korean officials said earlier this month that China had installed a steel structure in disputed waters west of South Korea, The Chosun Daily in Seoul reported.

Using reconnaissance satellites, South Korean intelligence agencies detected the structure last month and estimate that it exceeds 50 meters in width and height, The Chosun Daily said.

The structure was spotted in the disputed area known as the Provisional Measures Zone, or PMZ, in the Yellow Sea, which South Korea calls the Western Sea. The zone is where the exclusive economic zones of the two countries overlap.

The zone was established in 2001 to manage the overlapping claims to the area. Building any kind of facility and conducting activities unrelated to fishing are banned in the area until the dispute is settled.

China installed two similar structures in a nearby area in April and May, prompting protests by South Korea.

‘Gray zone strategy’

“It is likely that these recent actions are tied to a gray zone strategy that slowly encroaches on this area in ways that over the long-term reinforces their claims,” said Terence Roehrig, an Asia-Pacific security expert and lecturer at the University of Wisconsin-Madison.

“The goal of a gray zone strategy is to slowly force the target state to accept a new normal in the area. Seoul must ensure that does not happen by continuing to assert its position and insist that the delimitation of these waters be settled through negotiation,” Roehrig continued.

“China views the Yellow Sea as a crucial area for its security and potential gateway into the Chinese heartland. It is likely that eventually, these structures may have some military use,” he added.

Gray zone tactics blur the line between what is legal and illegal through paramilitary coercions designed to weaken an adversary over time. China’s tactics have included building artificial islands and making incursions, pushing the boundary of what is allowed to project military power and control sea routes.

“The incident demonstrates China is using the same strategy it employed in the South China Sea with South Korea now,” said Rahman Yaacob, research fellow for the Southeast Asia program at the Lowy Institute.

According to Yaacob, China has used gray tactics to build civilian structures in the South China Sea since the early 1990s. China installed structures in Mischief Reef back then, saying their purpose was to support fishermen, he said.

“We now know Mischief Reef has been converted into a military base on an artificial island,” Yaacob said.

China now has a military base on an artificial island it built on Mischief Reef, which is in the Spratly Islands. Mischief Reef is also claimed by multiple countries that protest China’s military buildup.

Admiral John Aquilino, the former U.S. Indo-Pacific commander, said in 2022 that China seemed to have completed the construction of missile arsenals, aircraft hangers, radar systems and other military facilities in Mischief Reef.

David Maxwell, vice president of the Center for Asia Pacific Strategy, said China might want access to “the mineral rights under the sea and to be able to transit freely in the area so it can control commerce and flow of activities in the area” close to South Korea.

Sustained structures in the region could impact naval operations of South Korea and the U.S., he continued.

“It’s important that South Korea, in particular, but also the United States, Japan and other allies do not allow China to normalize its activities,” Maxwell added. “That’s what it wants to do — normalize its presence so it can claim it as its sovereign [maritime] territory.”

In response to South Korea’s protests, China said last year that the structures were for supporting fishing activities. The Yellow Sea is a key fishing site for China.

“It’s certainly possible that the structures are used to support fishing activities,” said Tabitha Grace Mallory, a founder and CEO of China Ocean Institute and a University of Washington professor focusing on China’s ocean policy.

“The fact that these structures are being built unilaterally in the PMZ is just unnecessarily provocative,” she added.

Telling VOA on Tuesday that he is “not familiar with the situation,” Liu Pengyu, a spokesperson for the Chinese Embassy in Washington, said, “I would like to point out that China is a responsible country that has always carried out distant-water fishery and marine scientific activities in accordance with laws and regulations.”

Exploiting political turmoil

Some analysts say China could be taking advantage of Seoul’s political situation to install the structure in the disputed waters.

The installation coincides with the political chaos stemming from South Korean President Yoon Suk Yeol’s short-lived declaration of martial law.

“China is helping to create the political chaos in South Korea so that it can conduct these activities inside South Korea’s economic exclusive zone” and “act with impunity,” Maxwell said.

Others are unsure whether the two incidents are related.

“I don’t know if this is explicitly tied to exploiting [South Korea’s] political turmoil,” said Andrew Yeo, the SK-Korea Foundation chair in Korea studies at the Brookings Institution.

“But Beijing may be testing South Korea’s political resolve over disputed maritime claims, especially if we anticipate that the Trump administration will press [Seoul] to do more to counter Chinese threats in the Indo-Pacific,” Yeo continued.

Patrick Cronin, the Asia-Pacific security chair at the Hudson Institute, said Beijing does not want to push South Korea too hard, although it has an opportunity to do so, because “China has an interest in opening a healthy relationship with South Korea, especially at a time when it thinks it is going to have a more amendable government in place.”

Cronin was referring to main opposition Democratic Party leader Lee Jae-myung, considered pro-China, having a shot at running for the next presidential election, which could be held in few months if the Constitutional Court rules in favor of Yoon’s impeachment.