1. A weapon of mass destruction is a nuclear, radiological, chemical, biological or other weapon that can kill and bring significant harm to a large number of humans or cause great damage to human-made structures (e.g., buildings), natural structures (e.g., mountains), or the biosphere.
2. The scope and usage of the term has evolved and been disputed, often signifying more politically than technically. Originally coined in reference to aerial bombing with chemical explosives, since World War II it has come to refer to large-scale weaponry of other technologies, such as chemical, biological, radiological, or nuclear.
3. Weapon of mass destruction (WMD), weapon with the capacity to inflict death and destruction on such a massive scale and so indiscriminately that its very presence in the hands of a hostile power can be considered a grievous threat. Modern weapons of mass destruction are either nuclear, biological, or chemical weapons—frequently referred to collectively as NBC weapons.
4. The proliferation of nuclear weapons and other weapons of mass destruction (WMD), and their delivery systems, could have incalculable consequences for national, regional and global security. During the next decade, proliferation will remain most acute in some of the world’s most volatile regions.
5. With the dropping of the atomic bomb on Hiroshima, Japan, the fearsome power of conventional bombs paled before the spectacle of an entire city centre destroyed and some 66,000 people instantly killed by the blast and heat of a single nuclear weapon.
6. (By the end of the year, radiation injury brought the death toll to 140,000.) During the Cold War the United States, the Soviet Union, and other major powers built up enormous stockpiles containing tens of thousands of nuclear bombs, missile warheads, and artillery shells—so many that the military and diplomatic standoff of that era was sometimes described as a “balance of terror.”
7. At the same time both superpowers also amassed stockpiles of chemical and biological weapons, the two other principal types of modern WMD. Chemical weapons consist of liquids and gases that choke their victims, poison their blood, blister their skin, or disrupt their nervous system.
8. The relative ease with which both biological and chemical agents can be prepared, packaged, delivered, and set off have raised fears that they might become the weapon of choice of terrorists.
9. Indeed, since the end of the Cold War the main concern regarding all WMD has been proliferation, that is, the potential for lesser powers, “rogue states,” or international terrorist groups to acquire the means to produce and deliver WMD.