<!--Adopted by the UN Security Council on April 28, 2004, UN Resolution 1540 recognizes the threat posed to international peace and security by nuclear, chemical and biological weapons, as well as their means of delivery. It calls upon greater effort by nations to limit proliferation of such weapons.
Weapons of mass destruction, especially nuclear weapons, are rarely used because their use is essentially an "invitation" for a WMD retaliation, which in turn could escalate into a war so destructive it could easily destroy huge segments of the world's population. During the Cold War, this understanding became known as mutually assured destruction and was largely the reason war never broke out between the WMD-armed United States and Soviet Union.
Weapons of mass destruction are used to justify the Bush Doctrine of pre-emptive strikes against "rogue states" thought to be in danger of possessing or developing them. Opponents of this strategy note that the United States is the country that possesses one of the greatest arsenals of WMD on earth, and the only country that has ever used nuclear weapons in its attacks (at Hiroshima and Nagasaki), whereas others argue that the strategy is aimed solely at those whose intentions may be dangerous and that the current nuclear powers have all shown an unwillingness to use their WMD outside extreme circumstances, whereas the US has no similar guarantees with nations like North Korea.-->
