China’s defense ministry said on Friday that it yet again had to monitor and drive away the U.S. Navy destroyer USS Milius that entered its territorial waters in the South China Sea near the Paracel Islands.

“We sternly demand the U.S. to immediately stop such provocative acts, otherwise it will bear the serious consequences of unforeseen incidents,” a spokesperson said in a statement from the Ministry of National Defense.

The U.S. Navy said the guided-missile destroyer was asserting its navigational rights and freedoms.

“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 U.S. Navy Seventh fleet said in an emailed statement.

U.S. forces operate in the South China Sea on a daily basis, the U.S. Navy said.

It was the second straight day of a stand-off between the two super powers amid growing tensions in the South China Sea.

China claims vast swathes of the area that overlap with exclusive economic zones of various countries including the Philippines. Trillions of dollars in trade flow every year through the waterway.