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.
Iran and weapons of mass destruction
Iran states it has a legal right to enrich uranium for peaceful purposes under the NPT, and further says that it "has constantly complied with its obligations under the NPT and the Statute of the International Atomic Energy Agency". Twelve other countries are known to operate uranium enrichment facilities. Iran states that "the failure of certain Nuclear- Weapon States to fulfill their international obligations continue to be a source of threat for the international community". Iran also states that "the only country that has ever used nuclear weapons still maintains a sizable arsenal of thousands of nuclear warheads" and calls for a stop to the transfer of technology to non-NPT states. Iran has called for the development of a follow-up committee to ensure compliance with global nuclear disarmanent. Iran and many other nations without nuclear weapons have said that the present situation whereby Nuclear Weapon States monopolise the right to possess nuclear weapons is "highly discriminatory", and they have pushed for steps to accelerate the process of nuclear disarmament.