Shortly after its foundation, the PRC initiated its nuclear research programme under the guise of peaceful uses of nuclear energy in the early-1950s. During a Chinese Communist Party (CCP) Central Committee meeting held on 15 January 1955, Chairman Mao announced for the first time that China would develop its own strategic weapons including the nuclear bomb and missile. The decision to develop nuclear weapon was to be implemented within the 12-Year Science Plan presented in September 1956 to the Eighth Congress of the CCP. The search for uranium and preparation for nuclear research, development and manufacturing facilities began in 1954~55.
The PRC initially approached its ally the Soviet Union seeking for help on its nuclear programme in the early 1950s, but the request was refused by Moscow. After the death of Stalin in 1953, the PRC made the request again to the Soviet Union’s new leader Khrushchev, who turned down the request for a full nuclear weapon development programme, but agreed to help the PRC develop the atomic energy technology for civil uses. In January 1955, Beijing signed an agreement with Moscow to supply uranium to the Soviet Union in exchange for assistance on its nuclear research. In return Moscow supplied China with an experimental nuclear reactor and a cyclotron, and also agreed to provide technical documents and training. In 1956 the PRC government set up the 3rd Ministry of Machinery Industry (later renamed 2nd Ministry of Machinery Industry) to take the lead in its nuclear programme.
Initially the Soviet assistance in China’s nuclear programme was limited to the civil nuclear energy field. However, Moscow’s attitude shifted in 1957 when Khrushchev needed the support from the CCP leaders in dealing with the political struggle within his own party. In return, Moscow signed a comprehensive weapon technology transfer agreement with Beijing in October 1957 that included provision for additional Soviet nuclear assistance as well as the furnishing of some surface-to-surface, surface-to-air, and anti-ship missiles. Under the agreement, the Soviet Union promised to supply a sample atomic bomb and to provide technical assistance in the manufacture of nuclear weapons. The Soviet Union also sent advisers to help China build a major gaseous diffusion facility for production of enriched uranium.
The Soviet-supplied 7,000kW experimental heavy water nuclear reactor and 1.2m-diametre cyclotron became fully functional in June 1958 in Beijing 601 Plant, marking an important milestone in China’s nuclear programme. By then over 1,000 Soviet advisers had worked with the Chinese 2nd Ministry of Machinery Industry to assist its nuclear weapon development. China also began the construction of nuclear manufacture facilities including gaseous diffusion plant and nuclear test site in 1958.
The Soviet nuclear assistance slowed down in late 1958 as an early indicator of the political dispute between the Chinese and Soviet leaders. Moscow halted the delivery of the atomic bomb model and relevant technical documents to China, and has tighten up its control over the nuclear technology transfer. After the relation between the two communist countries finally broke up in October 1959, Moscow suspended its assistance to China and recalled all of its advisers. This has resulted in a major setback in China’s nuclear and other strategic weapon programme.
China managed to overcome the difficulties caused by the stop of Soviet assistance and continued its nuclear programme in the early 1960s. The development of the nuclear weapon was started in 1960 at Beijing Nuclear Weapon Research Institute (9th Bureau). In December 1962, the Chinese government decided to speed up the construction of the nuclear weapon R&D and manufacturing facility (Base 20) in Qinghai Province. The design proposal of China’s first atomic bomb was completed in March 1963. Lanzhou Gaseous Diffusion Plant (504 Plant) began to produce weapon-class enriched uranium in January 1964. Jiuquan Atomic Energy Complex also completed the development of relevant parts for the atomic bomb in 1964. Between 1960 and 1964, Chinese nuclear scientists carried out over 1,000 non-nuclear explosions to simulate the nuclear reaction process.
The preparation for China’s first nuclear test entered the final stage in 1964. In the Summer of 1964, three atomic devices were built and delivered to the Lop Nor nuclear test site. On 16 October 1964. China successfully exploded its first atomic bomb (Uranium 235) with a yield of 22kT. On 14 May 1965, the PLA Air Force (PLAAF) dropped a 35kT yield atomic bomb from a Tu-4 Bull bomber. The first successful test of an atomic warhead carried by a DF-2 medium-range surface-to-surface ballistic missile took place on 27 October 1966, marking the successful transformation from experimental nuclear devices to operational nuclear weapons in China's nuclear programme.
Even before the explosion of the first atomic bomb, development of the hydrogen (thermal nuclear) weapon was already underway. On 9 May 1965, a PLAAF H-6 bomber dropped a 25kT yield enhanced atomic bomb with thermal nuclear material (lithium 6). The test provided important data and experience for the hydrogen bomb development. The first full-yield thermal nuclear test was successfully carried out on 17 June 1967.
Since the late 1960s, China had conducted a range of air and ground nuclear explosions to test various designs. The series production of nuclear warhead for the DF-2 missile began in 1968. By the mid-1970s China was able to produce large (2,000~3,000kg), multi-megaton thermal nuclear warheads to be carried by its DF-3, DF-4 and DF-5 ballistic missiles. Development of the new-generation smaller warhead and neutron weapon began in the late 1970s. All nuclear tests after 1981 were underground (tunnel and shaft). The first low-yield neutron device was successfully tested on 29 September 1988.
From September 1992 to July 1996, China conducted a series of eight underground nuclear tests as part of its effort to develop smaller nuclear warheads to be carried by its new-generation solid-propellant ballistic missiles such as DF-21 and DF-31. These new warheads are believed to weight about 700kg, enabling multiple independently-targeted re-entry vehicle (MIRV) warheads to be carried by a single missile. In 1999, China claimed that it had already successfully developed the enhanced radiation nuclear weapon ("neutron bomb").
China signed the Comprehensive Nuclear Test Ban Treaty in September 1996, which prohibited future nuclear tests. By then, China had conducted a total of 45 nuclear tests, much less than the tests carried out by the United States (1,032 times) and the Soviet Union (715 times). China may have carried out research on “subcritical” low-level nuclear tests and non-nuclear tests as part of its continuing nuclear development programme.