Chigua Reef is one of the Spratly Islands contested by Viet Nam, China, Taiwan, Philippines and Malaysia. It is controlled by China who have built a small military installation here (probably to give legitimasy to their claims as reef is otherwise mostly under water). Just south of Chiqua Reef there was a naval clash in March 1988 between China and Viet Nam in which over seventy Vietnamese sailors were killed.
Picture
here, pictures of chinese training on Chigua and other reefs
here.
http://www.reuters.com/article/us-southchinasea-china-arms-exclusive-idUSKBN1431OK