Abstract: This paper discusses Vietnam’s security cooperation with the United States in three phases. Following the end of the Vietnam War in the 1970s, Vietnam and the United States normalized their diplomatic relations in 1995 and took their first step towards security cooperation. Initially, the cooperation was implemented highly incrementally due to deep-rooted mutual distrust. Vietnam’s security cooperation with the United States made significant strides with the reemergence of the South China Sea issue. The U.S.-Vietnam security cooperation advanced rapidly, fueled by the convergence of the two countries’ strategic interests in the South China Sea. The 2014 oil rig incident triggered Vietnam to promote further convergence with the United States. The first visit to the United States by the General Secretary of the Communist Party of Vietnam was materialized in July 2015. In May 2016, the United States declared the complete lifting of the arms embargo on Vietnam. Such developments created the impression of convergence between the United States and Vietnam. While Vietnam has steadily fostered security cooperation with the United States following the inauguration of the Trump administration, it will likely continue to pursue omnidirectional external relations and give further considerations to achieving a balance in external relations, especially between the Vietnam-U.S. and Vietnam-China relationships. Full text available here.