Crew members work at a control room on the patrol vessel Haixun-21 on the South China Sea in south China, April 22, 2015. The 93-meter-long Haixun-21 is China's first patrol vessel with displacement exceeding 1,000 tons and capable of carrying helicopters. The 1,500-ton-displacement vessel, which was built in 2001 and then served in East China Sea, has participated more than 100 missions since it was transferred to the South China Sea in 2012. Haixun-21 and Haixun-1103 set out for a 3-day patrol mission on the waters of Xisha Islands in South China Sea on April 21. (Photo: Xinhua/Guo Qiuda)
