China's Liaoning aircraft carrier and its escorts head back to Qingdao on Jan. 1 after completing sea trials in the South China Sea. (Photo/CNS)After Vietnam received its first Kilo-class submarine in November, China has adopted an underwater strategy to monitor the activities of foreign submarines in the disputed South China Sea, writes US defense expert Harry Kazianis for the Tokyo-based Diplomat magazine. Quoting an article written by Lyle Goldstein and Shannon Knight for the United States Naval Institute’s Proceedings magazine, Kazianis noted that China has deployed fixed ocean-floor acoustic arrays off its coastline, while research suggests that China is deploying the new system for anti-submarine warfare. Kazianis praised the work of Goldstein and Knight, which cited several Chinese-language journals such as Shandong Science, China Science Daily, Naval and Merchant Ships and Ship Electronic Engineering. He added that their research has shown that China is now hard at work deploying ocean-floor surveillance systems in its proximate waters. More