China has said military construction on the islands it controls in the sea will be limited to defensive requirements, and that it can do what it likes on its own territory.
The United States has criticized what it has called China's militarization of its maritime outposts and stressed the need for freedom of navigation by conducting periodic air and naval patrols near them that have angered Beijing.
The Defence Times newspaper said Norinco CS/AR-1 55mm anti-frogman rocket launcher defense systems with the capability to discover, identify and attack enemy combat divers have been installed on Fiery Cross Reef in the Spratly Islands. Fiery Cross Reef is administered by China but also claimed by the Philippines, Vietnam and Taiwan.
The report did not say when the defense system was installed, but said it was part of a response that began in May 2014 when Vietnamese divers installed large numbers of fishing nets in the Paracel Islands.
China has conducted extensive land reclamation work at Fiery Cross Reef, including building an airport.