United States and weapons of mass destruction
The United States is known to have possessed three types of weapons of mass destruction: nuclear weapons, chemical weapons, and biological weapons. The U.S. is the only country to have used nuclear weapons in combat, when it detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki during World War II. It had secretly developed the earliest form of the atomic weapon during the 1940s under the title "Manhattan Project". The United States pioneered the development of both the nuclear fission and hydrogen bombs (the latter involving nuclear fusion). It was the world's first and only nuclear power for four years (1945–1949), until the Soviet Union managed to produce its own nuclear weapon. The United States has the second largest number of deployed nuclear weapons in the world, after Russia.
Nuclear weapons and the United Kingdom
The United Kingdom is one of the five nuclear-weapon states legally recognised as such under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). , nine countries have nuclear weapons. After the UK government announced its plans to refurbish its Trident missiles and build new submarines to carry them, it published a white paper on "The Future of the United Kingdom's Nuclear Deterrent", in which it stated that the renewal is fully compatible with the United Kingdom's treaty commitments and international law. At the start of the House of Commons debate to authorise the replacement of Trident, Margaret Beckett, the Secretary of State for Foreign and Commonwealth Affairs, stated: