Officer Liu Tang, right, who has been stationed on the Nansha and Xisha Islands for 20 years in his 32 years' military career, directs a training task for the navy soldiers in Sansha, South China's Hainan province, on May 24, 2013. [Photo/Xinhua]
Sentries patrol along the sovereign stone tablet on Shidao Islet, affiliated to the Xisha Islands, in the South China Sea, on May 24, 2013. [Photo/Xinhua]