The United States Department of Defense has warned that China's test launches of ballistic missiles in the South China Sea were a threat to peace and security in the region.
The Chinese military launched four medium-range missiles from mainland China on Wednesday. The missiles are said to have impacted the northern reaches of the South China Sea between Hainan Island and the Paracel Islands, known as the Xisha Islands in China.
A statement issued by the Pentagon said: "Conducting military exercises over disputed territory in the South China Sea is counterproductive to easing tensions and maintaining stability."
The Pentagon described the drills as the latest in a long string of Chinese actions intended to "assert unlawful maritime claims" that disadvantage neighbouring countries.
"Such exercises also violate the People's Republic of China commitments under the 2002 Declaration on the Conduct of Parties in the South China Sea to avoid activities that would complicate or escalate disputes and affect peace and stability."
Wednesday's tests come a month after two US aircraft carrier strike groups, led by the USS Nimitz and USS Ronald Reagan, completed combined exercises in the South China Sea for the first time in six years.
The US has increased its naval activity in the region in recent months, carrying out routine patrols, referred to as freedom of navigation operations.
Home to vital international shipping lanes, the South China Sea is widely deemed as a potential flashpoint for a military conflict between the US and China
Over the past decade China has built up military installations on several disputed reefs and outcrops in the South China Sea to assert its claim over much of the area.
Meanwhile, Beijing has criticised Washington over its blacklisting of two dozen state-owned Chinese companies involved in building and supplying China's South China Sea bases.
The 24 state-owned firms include subsidiaries of construction giant China Communications Construction Co., telecommunications firms and a unit of the China Shipbuilding Group.
The US Commerce Department said the companies "enabled China to construct and militarise disputed outposts in the South China Sea.
Foreign Ministry Spokesman Zhao Lijian said: "China will take firm measures to uphold the legitimate rights and interests of Chinese companies and individuals
China has secretly increased tests of ballistic missiles, as part of a wider strategy to measure their operational capabilities. The country fired off in excess of 100 ballistic missiles last year, more than three times North Korea's record tally, Kyodo News reported in February.