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 Israel
In a statement to the May 2009 preparatory meeting for the 2010 NPT Review Conference, the US delegation reiterated the longstanding US support for "universal adherence to the NPT", but uncharacteristically named Israel among the four countries that have not done so. An unnamed Israeli official dismissed the suggestion that it would join the NPT and questioned the effectiveness of the treaty. "The Washington Times" reported that this statement threatened to derail the 40-year-old secret agreement between the US and Israel to shield Israel's nuclear weapons program from international scrutiny. According to Avner Cohen, by not stating that Israel has atomic weapons, the US avoids having to sanction the country for violating American non-proliferation law. Cohen, author of "Israel and the Bomb", argued that acknowledging its nuclear program would allow Israel to take part constructively in efforts to control nuclear weapons.