Beijing has called the presence of a US warship near a disputed island in the South China Sea "a serious political and military provocation". The USS Stethem sailed close to Triton Island, part of the Paracel Islands archipelago, claimed by China and others. China responded by sending military vessels and fighter jets to the area. It happened hours before US President Donald Trump and Chinese counterpart Xi Jinping spoke on the phone. During the call, Mr Xi told Mr Trump that "negative factors" were affecting US-China relations, according to a read-out of the call carried on Chinese state TV.