US coastguard ship Bertholf maneouvers during a joint exercise in South China Sea. Photograph:( AFP )
The South China Sea is one of a growing number of flashpoints in the US-China relationship, which include a trade war, US sanctions and Taiwan.
The Pentagon said on Tuesday a recent Chinese missile launch in the disputed South China Sea was "disturbing" and contrary to Chinese pledges that it would not militarise the disputed waterway.
China and the United States have repeatedly traded barbs in the past over what Washington says is Beijing's militarization of the South China Sea by building military installations on artificial islands and reefs.
A US official, speaking on the condition of anonymity, said China tested multiple anti-ship ballistic missiles over the weekend.
"Of course the Pentagon was aware of the Chinese missile launch from the man-made structures in the South China Sea near the Spratly Islands," Pentagon spokesman Lieutenant Colonel Dave Eastburn said.
"I'm not going to speak on behalf of all the sovereign nations in the region, but I'm sure they agree that the PRC's behaviour is contrary to its claim to want to bring peace to the region and obviously actions like this are coercive acts meant to intimidate other (South China Sea) claimants," Eastburn added. PRC is an acronym for the People's Republic of China.
China has not confirmed the missile tests and on Tuesday the foreign ministry declined to comment, referring questions to the defence ministry, which did not respond to a request for comment.
The Chinese government has said that the military was carrying out drills between the Spratly and Paracel Islands starting last weekend and ending on Wednesday, warning other shipping not to enter a designated area.
China's claims in the South China Sea, through which about $5 trillion in ship-borne trade passes each year, are contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.
News of the China missile test was first reported by NBC News.