The U.S. reportedly sailed two Navy ships past disputed islands in the South China Sea on Sunday, a move meant to rebuff Beijing's claim to the territory.
A U.S. official told CNN the USS Higgins and the USS Antietam sailed past the Paracel Islands in what's called a "freedom of navigation operation" — an intentional pass-by of the islands meant to snub China's claim to the territory and treat it as international waters.
China occupies the islands and claims they belong to Beijing. The U.S., however, doesn't see it that way. It doesn't recognize official ownership of the islands and notes that Vietnam also claims them.
China said the operation was a "serious infringement" on China's sovereignty. Its national defense ministry said Chinese ships went to identify the American ships and "warn them off." A spokesperson said the move "undermined strategic mutual trust between the two militaries and damaged peace, security and good order in relevant waters.