US Navy keeps closer watch on China submarines, Beijing think tank says

The United States' surveillance of China's submarines is happening far more often in the South China Sea , a think tank says, a sign that military activity between the two countries is heating up under the water. The US has five USNS (United States Naval Ship) ocean surveillance vessels - Victorious, Able, Effective, Loyal and Impeccable - stationed in Japan . The ships, which can be used in anti-submarine warfare , were tracked operating in the South China Sea for at least 161 days out of 181 days in the first half of this year, according to a report from…