South Korea Raises Alarm Over China’s No-Sail Zone in Shared Yellow Sea Waters

South Korea has expressed growing concern after China unilaterally declared a “no-sail zone” in a sensitive area of the Yellow Sea where the two countries’ maritime borders overlap. The move has triggered diplomatic exchanges, as Seoul questions the legality and intent behind China’s actions in the contested waters.

The area in question lies within what is known as the Provisional Measures Zone (PMZ), a maritime space where the exclusive economic zones (EEZs) of both China and South Korea overlap. Although both countries are technically allowed to carry out military drills in this shared zone, China’s recent decision to restrict access has raised serious questions in Seoul.

According to South Korea’s foreign ministry, China’s declaration of a no-sail zone appeared to be made without adequate consultation and could potentially violate the principle of freedom of navigation. The restrictions, which were reportedly in effect until May 27, prompted South Korea to lodge a formal diplomatic protest with Beijing.

While China’s Maritime Safety Administration did not provide an official reason for the no-sail order, South Korean maritime authorities suggested it may have been linked to Chinese military exercises. If confirmed, this would not be unprecedented — both nations occasionally conduct drills in the PMZ. However, what sets this incident apart is the scope and lack of transparency surrounding the Chinese move.

Adding to the tensions, there have been reports of China constructing three unidentified structures in the same disputed zone. Chinese authorities have labeled them as “aquaculture facilities,” but South Korean experts suspect they could be part of a broader strategy known as “grey zone” tactics — ambiguous actions that stop short of open conflict but serve to assert control and shift the status quo in China’s favor.

South Korea has voiced concerns that these developments could be part of a deliberate effort by China to expand its maritime claims under the radar of international scrutiny. The foreign ministry in Seoul emphasized that it is closely coordinating with its defense and maritime agencies to evaluate whether the Chinese actions align with international maritime law.

The incident has reignited broader worries in the region over China’s assertive behavior in contested waters, not only in the Yellow Sea but also in the South and East China Seas, where similar disputes have unfolded in recent years. While no direct confrontation has occurred, South Korea’s latest move to challenge China diplomatically signals a readiness to defend its maritime interests more firmly.

As the situation continues to evolve, both countries are expected to engage in further dialogue. However, the underlying tension in the Yellow Sea underscores the fragile nature of maritime cooperation in the region — and the growing strategic importance of even the most seemingly routine moves at sea.