On May 21, 2025, China’s Maritime Safety Administration (MSA) declared a “no-sail zone” in the Yellow Sea, known as the West Sea in Seoul. This declaration applies within the Provisional Measures Zone (PMZ), a maritime area in the center of the Yellow Sea where the exclusive economic zones (EEZs) of China and South Korea overlap. Previously, China built three steel structures on its side of the PMZ. This article analyzes the implications of the steel structure installations and the no-sail zone in the PMZ, as well as whether China’s suspension of high seas freedoms violates international maritime law, particularly the United Nations Convention on the Law of the Sea (UNCLOS). This analysis examines the legal and strategic implications to determine if China’s actions comply with international law.
Both China and South Korea are parties to UNCLOS, which governs the Yellow Sea, also known as the West Sea. The Yellow Sea lies between mainland China and the Korean Peninsula. This body of water is surprisingly large, covering 380,000 km² (150,000 sq mi), compared to 251,000 km² (97,000 sq mi) for the Persian Gulf.
