Republic of Korea (ROK) officials have noted China’s “creeping sovereignty” in the Yellow Sea, which Koreans call the West Sea, the Center for Strategic and International Studies (CSIS) reported.
The United States-based think tank found that Beijing has deployed maritime structures within an agreed-upon Provisional Measures Zone (PMZ) in the contested waters between China and the Korean Peninsula, raising significant legal concerns under the 2001 Korea-China Fisheries Agreement and the United Nations Convention on the Law of the Sea (UNCLOS).
Seoul and Beijing designed the fisheries agreement to address their overlapping exclusive economic zone (EEZ) claims, establishing the PMZ as a jointly managed area. The pact explicitly prohibits permanent installations within the PMZ, a provision intended to prevent either nation from unilaterally asserting jurisdiction or altering the status quo. Despite this, China since 2018 has deployed 13 buoys, two large aquaculture cages, and a maintenance and management platform without ROK consultation. Beijing asserts the installations are for civilian aquaculture and scientific purposes and therefore do not violate the agreement.
The platform moved to a shipyard on China’s mainland in late January 2026. Beijing maintained that a private entity, not the government, commissioned the relocation, according to the CSIS.
Beyond China’s unilateral actions, which the PMZ is intended to prevent, Seoul perceives Beijing as attempting to gradually expand its sovereignty across the Yellow Sea. The ROK repeatedly has requested China remove or relocate the maritime structures, but China has refused and instead declared unilateral no-sail zones while expanding its presence in the PMZ. In addition, China Coast Guard vessels have intercepted ROK monitoring efforts more than 25 times since 2020. In September 2025, China Coast Guard ships followed an ROK research vessel for over 15 hours after it approached the platforms for observation.
Seoul views Beijing’s actions as not only contrary to the 2001 agreement but also as violations of UNCLOS. Under the international legal framework, coastal states have exclusive rights in their EEZs to explore, exploit, conserve and manage natural resources, although these rights do not equate to full sovereignty.
Importantly, UNCLOS guarantees freedom of navigation and overflight for all states within EEZs. China’s declaration of no-sail zones and its use of coast guard vessels to intercept and shadow ROK research and government vessels in the PMZ mirrors the creeping sovereignty and gray-zone tactics China employs in the East China and South China seas. There, Beijing asserted de facto control after structures were militarized, fundamentally altering the strategic landscape of contested waters by using an unfounded interpretation of international law. The global community has repeatedly condemned such tactics as contrary to the principles of peaceful dispute resolution and good faith under international law.
As the CSIS reported in December 2025, the ROK seeks to maintain freedom of navigation in the Yellow Sea. But Beijing, by deploying and defending structures in contested waters, attempts to make permanent, strategic gains through violations of international law and the bilateral fisheries agreement. The situation merits close attention from the international community as the U.S. and its Allies and Partners seek to preserve a Free and Open Indo-Pacific.