Status of marine structures installed by China in the Yellow Sea. Yonhap News

A US expert on the Korean Peninsula has called for strong action against China's unauthorized installation of structures in the South China Sea's South Korean-Chinese Interim Measures Zone (PMZ) in recent years, characterizing it as a "grey zone tactic" that falls between wartime and peacetime operations.

In an article posted on "Beyond Parallel," a North Korea-focused website of the Center for Strategic and International Studies (CSIS), Victor Cha, the Korea Chair at the US think tank, stated on the 9th (local time) that "the United States must define China's actions as a Chinese grey zone tactic targeting its Indo-Pacific partners."

Grey zone tactics refer to coercive actions that weaken an adversary using non-military means without provoking traditional armed conflict.

Cha stated, "Washington (the US) and Seoul (South Korea) should consider publicly releasing the coordinates of the Chinese structures for public use and analysis," and added, "The United States must support South Korea's claims regarding China's unilateral violation of the PMZ agreement."

He particularly emphasized, "In essence, what the US's new National Security Strategy (NSS, released on the 5th) demands in the South China Sea also applies to South Korea and the US's efforts to maintain freedom of navigation in the Yellow Sea," and stressed, "Strong measures must be in place, along with the necessary deterrence, to keep these routes open, freely passable, and to prevent them from being arbitrarily closed by any one nation."

Status of marine structures installed by China in the Yellow Sea. Yonhap News 

Cha pointed out that China's installation of two large deep-sea aquaculture structures, "Shen Lan," and a large structure named "Atlantic Amsterdam" within the PMZ, without prior consultation with South Korea, "violates the South Korea-China Fisheries Agreement, which prohibits the installation of permanent structures within the PMZ."

Cha also revealed, "Of the 135 attempts by South Korean vessels to investigate China's activities since 2020, 27 were blocked by the Chinese Coast Guard. This includes multiple instances where South Korea's research vessel Onnuri encountered the Chinese Coast Guard this year."

He further noted, "While this is not a technical violation of the Fisheries Agreement or the UN Convention on the Law of the Sea (UNCLOS)," he observed, "the installation of civilian facilities for potentially dual-use purposes and China's harassment of South Korean vessels are similar to the 'gradual expansion of sovereignty' grey zone tactics that Beijing (China) employed when militarizing islands and reefs in the South China Sea and East China Sea."