CSIS – The United States should flag this activity as another example of China’s grey zone tactics targeting Indo-Pacific partners. Washington and Seoul should consider releasing the coordinates of the Chinese structures for public use and analysis. Washington should support any South Korean claims of unilateral violations of the PMZ agreement by China. In sum, what the new National Security Strategy mandates for the South China Sea is applicable to U.S. and South Korean efforts to maintain freedom of navigation in the Yellow Sea.