China warned the US on Friday that there would be "serious consequences" after a US warship entered waters claimed by Beijing, ramping up already heightened tensions.
The US Navy destroyer USS Milius sailed around the disputed Paracel Islands in the South China Sea for the second day in a row, in a move that Beijing described as violating China's sovereignty.
What Beijing said
"We sternly demand the US to immediately stop such provocative acts, otherwise it will bear the serious consequences of unforeseen incidents," Chinese Ministry of National Defense spokesperson Tan Kefei said.
"The act of the US military seriously violated China's sovereignty and security, severely breached international laws, and is more ironclad evidence of the US pursuing navigation hegemony and militarizing the South China Sea," he added.
China said that it chased off the USS Milius, a claim that the US Navy denies.
Why was the US warship near the Paracel Islands?
The guided-missile destroyer was asserting navigational rights and freedoms in the contested area, according to the US Navy.
"Unlawful and sweeping maritime claims in the South China Sea pose a serious threat to the freedom of the seas, including the freedoms of navigation and overflight, free trade and unimpeded commerce, and freedom of economic opportunity for South China Sea littoral nations," the US Navy 7th fleet said in a statement.
The US Navy has a regular presence in the South China Sea, although Washington has no territorial claims there.
The strategic waterway is a path of transit for around $5 billion (€4.62 billion) every year, as well as being highly valued for its fish stock and mineral resources.
The question of sovereignty over numerous small islands in the South China Sea has been one of the main sources of tension between the two superpowers, along with the fate of Taiwan.
China has laid claim to large maritime regions that overlap the exclusive economic zones of other countries in the region — including US allies such as the Philippines.
A recent series of events have ramped up tensions between Washington and Beijing, including the shooting down of an alleged Chinese spy balloon in US airspace, China's support for Russia amid the war in Ukraine and visits by leading US figures to Taiwan — another island Beijing considers part of its territory.