Two US warships sailed through the sensitive Taiwan Strait on Thursday drawing protest from Beijing, the second such mission this month and coming almost two weeks after a Chinese aircraft carrier group used the same waterway.
China, which claims democratically run Taiwan as its own territory, has been angered by stepped-up US support for the island, including arms sales and sailing warships through the Taiwan Strait, further souring Beijing-Washington relations.
The US Navy said the guided-missile destroyers USS John S. McCain and USS Curtis Wilbur had "conducted a routine Taiwan Strait transit Dec. 31 in accordance with international law".
"The ships' transit through the Taiwan Strait demonstrates the US commitment to a free and open Indo-Pacific. The United States military will continue to fly, sail and operate wherever international law allows."
This is the 13th sailing through the strait by the US Navy this year.
China's Defence Ministry denounced the trip as "provocation" and "a show of force", adding Chinese ships and aircraft trailed the US ships.
The passage of the ships sent the wrong message to supporters of Taiwan independence and are a serious threat to peace and stability, it added.
"The Chinese People's Liberation Army maintains a high level of alert at all times, responds to all threats and provocations at all times, and resolutely defends national sovereignty and territorial integrity," the ministry said.
Taiwan's Defence Ministry said the ships had sailed in a northerly direction through the strait on what it termed an "ordinary mission". Taiwan's armed forces monitored the sailing and the situation is "as normal", it added.
China's military said it had tailed the last US warship to pass through the Taiwan Strait on Dec. 19, and denounced the mission.
The day after that trip, Taiwan's navy and air force deployed as a Chinese aircraft carrier group led by the country's newest carrier, the Shandong, sailed through the Taiwan Strait.
China said the group was on its way to routine drills in the disputed South China Sea.