Overview
639 was the codename for China's first full-scale test of a two-staged thermonuclear device, on 17 June 1967, yielding 3.3 megatons of TNT. The sixth nuclear test carried out by the People's Republic of China, it was parachuted from a Xi'an H-6 bomber over the Lop Nur Nuclear Test Base in Xinjiang, detonating at a height of 3 km.