The Pentagon said the USS Stethem destroyer and the USNS Cesar Chavez cargo ship conducted a "routine transit" between the South China Sea and the East China Sea through the Taiwan Strait Sunday through Monday.

"We resolutely oppose some of the provocative actions taken by the US that are not conducive to the stability of the Taiwan Strait, and to the China-US relations," foreign ministry spokesman Lu Kang said at a regular press briefing.

Lu said Beijing had lodged an official diplomatic protest with the United States.

In recent months, US Navy ships have repeatedly passed through the waterway, which separates mainland China from the self-ruled democratic island.

Beijing views any ships passing through the strait as essentially a breach of its sovereignty -- while the US and many other nations view the route as international waters open to all.

China sees Taiwan as part of its territory to be reunified, despite the two sides being ruled separately since the end of a civil war on the mainland in 1949.