This Overview shows dozens of Chinese ships anchored at Whitsun Reef in the South China Sea, roughly 200 miles (322 km) west of Palawan Island, of the Philippines. Ownership of this reef and the surrounding Spratly Islands is contested by China, the Philippines and other nearby nations. The arrival of these Chinese ships in March 2021 has spurred a diplomatic incident, causing the United States to warn China against further aggressive moves in the region.