In the post–World War II period, extensive negotiations have taken place concerning arms control and disarmament, for the most part under the auspices of the United Nations General Assembly, at least as far as world-wide arrangements are concerned. The greatest part of these negotiations has focused on nuclear weapons, less often on chemical or biological weapons, and relatively infrequently on other types of arms (see Table 2.1).

Although not defined formally in any legal instrument, nuclear, chemical, and biological weapons have come to be known collectively as “weapons of mass destruction” in contrast to the others, called “conventional weapons.” The former term evidently reflects the fact that these weapons can cause destruction (in the case of nuclear weapons) and death (in the case of all three types) on a massive scale. These weapons also have the characteristic that, even if not used in large quantities, they tend to be indiscriminate, in particular in affecting civilians even more than military personnel, as the latter are more likely to use protective gear. Of course, this is not necessarily so: A nuclear weapon used against a warship at sea will probably kill or injure only military personnel. By contrast, most conventional weapons, when properly used, permit discrimination among targets – though land mines often do not, as a result of which treaties have recently been concluded to ban or severely restrict them.