The US Defense Department on Wednesday said commercial imagery indicated that China had deployed a surface-to-air missile system on a disputed outpost in the South China Sea, and said the action was increasing tensions in the region.
The Pentagon urged all countries that have staked claims to disputed areas in the region to address their territorial and maritime claims in accordance with international law, and to commit to peacefully manage or resolve their disputes.
"We call on South China Sea claimants to publicly commit to a reciprocal halt to further land reclamation, construction of new facilities, and new militarization of disputed features," said Navy Commander Bill Urban, a spokesman for the Pentagon.
Earlier a US official said it was unclear whether the deployment is intended for the long-term. The official was not authorised to discuss the information publicly and so spoke on condition of anonymity.
Asked about the reported deployment, Secretary of State John Kerry voiced serious concern over increasing militarisation by Beijing in the South China Sea.
He said that contradicted a public assurance from Chinese President Xi Jinping when he visited the White House last September.
The deployment follows China's building of new islands by piling sand atop reefs and then adding airstrips and military installations.
The buildup is seen as part of Beijing's efforts to claim virtually the entire disputed sea and its resources, which has prompted some of its wary neighbours to draw closer to the US.
In Beijing, Chinese Foreign Minister Wang Yi accused the media of hyping the issue and saying more attention should be paid to the "public goods and services" provided by China's development of its maritime claims.
