Test No. 6 is the codename for China's first test of a three-staged thermonuclear device and, also its sixth nuclear weapons test. The device was detonated at Lop Nur Test Base, or often dubbed as Lop Nur Nuclear Weapon Test Base, in Malan, Xinjiang, on 17 June 1967. With successful testing of this three-stage thermonuclear device, China became the fourth country to have successfully developed a thermonuclear weapon after the United States, Soviet Union and the United Kingdom. It was dropped from a Hong-6 (Chinese manufactured Tu-16) and was parachute-retarded for an airburst at 2960 meters. The bomb was a three-stage device with a boosted U-235 primary and U-238 pusher. The yield was 3.3 megatons.