OT II afternoon/evening

United States

Main articles: Nuclear weapons and the United States and United States and weapons of mass destruction

The United States developed the first atomic weapons during World War II in co-operation with the United Kingdom and Canada as part of the Manhattan Project, out of the fear that Nazi Germany would develop them first. It tested the first nuclear weapon in 1945 ("Trinity"), and remains the only country to have used nuclear weapons against another nation, during the atomic bombings of Hiroshima and Nagasaki. It was the first nation to develop the hydrogen bomb, testing an experimental version in 1952 ("Ivy Mike") and a deployable weapon in 1954 ("Castle Bravo"). Throughout the Cold War it continued to modernize and enlarge its nuclear arsenal, but from 1992 on has been involved primarily in a program of Stockpile stewardship.[6][7][8] At its Cold War height, the US nuclear arsenal is estimated to have contained over 32,000 warheads (in 1966).[

9 Soviet Union / Russian Federation

The United Kingdom tested its first nuclear weapon ("Hurricane") in 1952, drawing largely on data gained while collaborating with the United States during the Manhattan Project. The United Kingdom was the third country in the world after the USA and USSR to develop and test a nuclear weapon. Its programme was motivated to have an independent deterrent against the USSR, while also maintaining its status as a great power. It tested its first hydrogen bomb in 1957 (Operation Grapple), making it the third country to do so after the USA and USSR.[11][12] The UK maintained a fleet of V bomber strategic bombers and ballistic missile submarines (SSBNs) equipped with nuclear weapons during the Cold War. It currently maintains a fleet of four 'Vanguard' class ballistic missile submarines equipped with Trident II SLBMs. The British government announced a replacement to the current system to take place between 2007-20

France

Main article: France and weapons of mass destruction

France tested its first nuclear weapon in 1960 ("Gerboise Bleue"), based mostly on its owresearch.It was motivated by the Suez Crisis diplomatic tension vis-à-vis both the USSR and the Free World allies United States and United Kingdom. It was also relevant to retain great power status, alongside the United Kingdom, during the post-colonial Cold War (see: Force de frappe).

China

Main article: People's Republic of China and weapons of mass destruction

China tested its first nuclear weapon device ("596") in 1964 at the Lop Nur test site. The weapon was developed as a deterrent against both the United States and the Soviet Union. Two years later, China had a fission bomb capable of being put onto a nuclear missile.

India

. The U.S. State Department said it made it "very clear that we will not recognize India as a nuclear-weapon state".[28] The United States is bound by the Hyde Act with India and may cease all cooperation with India if India detonates a nuclear explosive device. The US had further said it is not its intention to assist India in the design, construction or operation of sensitive nuclear technologies through the transfer of dual-use items.[29] In establishing an exemption for India, the Nuclear Suppliers Group reserved the right to consult on any future issues which might trouble it.[30] As of June 2011, India was estimated to have had a stockpile of around 80–100 warheads.[4]

Pakistan

In 2004, the Pakistani metallurgist A.Q. Khan, a key figure in Pakistan's nuclear weapons program, confessed to heading an international black market ring involved in selling nuclear weapons technology. In particular, Khan had been selling gas centrifuge technology to North Korea, Iran, and Libya. Khan denied complicity by the Pakistani government or Army, but this has been called into question by journalists and IAEA officials, and was later contradicted by statements from Khan himself.[32]

North Korea

However, in October 2006, North Korea stated that due to growing intimidation by the USA, it would conduct a nuclear test to confirm its nuclear status. North Korea reported a successful nuclear test on October 9, 2006 (see 2006 North Korean nuclear test). Most U.S. intelligence officials believe that North Korea did, in fact, test a nuclear device due to radioactive isotopes detected by U.S. aircraft; however, most agree that the test was probably only partially successful.[33] The yield may have been less than a kiloton, which is much smaller than the first successful tests of other powers; however, boosted fission weapons may have an unboosted yield in this range, which is sufficient to start deuterium-tritium fusion in the boost gas at the center; the fast neutrons from fusion then ensure a full fission yield. North Korea conducted a second, higher yield test on May 25, 2009 (see 2009 North Korean nuclear test).

Israel

Israel is not a party to the Nuclear Non-Proliferation Treaty. Israel has pledged not to be the first country to introduce nuclear weapons into the region, but engages in strategic ambiguity by refusing to confirm or deny a nuclear weapons program or arsenal. This policy of "nuclear opacity" has been interpreted as an attempt to get the benefits of deterrence with a minimum political cost.[34] In the late 1960s, Israeli Ambassador to the US Yitzhak Rabin informed the United States State Department that "introducing" nuclear weapons would constitute testing and public declaration, and mere possession would be excluded from the pledge.[35] There is extensive evidence Israel has nuclear weapons or a near-ready nuclear weapons capability. Israel may have tested a nuclear weapon along with South Africa in 1979, but this has never been confirmed, and interpretation of the Vela Incident is controversial. The stated purpose of the Negev Nuclear Research Center near Dimona is to advance basic nuclear science and applied research on nuclear energy.[36] Extensive information about the program in Dimona was disclosed by technician Mordechai Vanunu in 1986.[37][38]