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.
Treaty on the Non-Proliferation of Nuclear Weapons
Over the years the NPT has come to be seen by many Third World states as "a conspiracy of the nuclear 'haves' to keep the nuclear 'have-nots' in their place". This argument has roots in Article VI of the treaty which "obligates the nuclear weapons states to liquidate their nuclear stockpiles and pursue complete disarmament. The non-nuclear states see no signs of this happening". Some argue that the NWS have not fully complied with their disarmament obligations under Article VI of the NPT. Some countries such as India have criticized the NPT, because it "discriminated against states not possessing nuclear weapons on January 1, 1967," while Iran and numerous Arab states have criticized Israel for not signing the NPT. There has been disappointment with the limited progress on nuclear disarmament, where the five authorized nuclear weapons states still have 22,000 warheads among them and have shown a reluctance to disarm further.