The Yellow Sea is a gateway to both Beijing and Seoul (see map). China’s northern fleet has its headquarters on the Yellow Sea coast; on the other side of it sits Incheon, South Korea’s second-largest deepwater port and the site of a famed battle in 1950 during the Korean war. Camp Humphreys, America’s largest overseas military base, is located inland only 15km from the Yellow Sea’s shore. China and South Korea claim overlapping exclusive economic zones in the centre of the sea. They agreed in 2001 that they would jointly manage fisheries in an area known as the Provisional Measures Zone (PMZ).
“[…] the behaviour fits an ominous pattern. Goings-on in the South China Sea ‘started out exactly the same way, with China saying this is entirely civilian’, says Victor Cha of the Centre for Strategic and International Studies, an American think-tank. In those waters, fishing huts placed on uninhabited shoals eventually begat air strips; oil rigs became instruments to assert sovereignty within the ‘nine-dash line’ that China marks on its own maps. China’s sensor-laden meteorological buoys around the PMZ could be reconfigured to ‘detect and monitor the movements of submarines and naval ships’, says Kim Suk-kyoon, a South Korean former coast guard chief. South Korea’s parliament passed a resolution calling the structures a ‘violation of maritime rights’.”
https://www.economist.com/asia/2026/01/15/china-is-testing-south-korea-in-the-yellow-sea
See also: Creeping Sovereignty? China’s Maritime Structures in the Yellow Sea (West Sea)