Johnson South Reef, also known in Mandarin Chinese: 赤瓜礁; pinyin: Chìguā Jiāo; Mabini Reef (Filipino: Bahura ng Mabini, lit. 'Reef of Mabini'); Vietnamese: Đá Gạc Ma), is a reef in the southwest portion of the Union Banks in the Spratly Islands of the South China Sea. It is controlled by the People's Republic of China (PRC), but its ownership is disputed and also claimed by the Philippines, Taiwan (ROC), and Vietnam.