Neutrality has been one of the most enduring features in the history of international relations. The desire of individuals, groups or states to stand aside from the conflicts that convulse their neighbours is a natural one. Self-preservation and the wish to avoid the deprivation and hardship that so often accompany wars generally prevail over the temptation to enter the fray. Although various attempts have been made to outlaw war from international relations, war has remained an accepted, common, and perhaps even natural way for states to pursue their interests on the international stage. In these circumstances, the recourse to neutrality has generally been considered an entirely legitimate and appropriate form of behaviour. Neutrality's impact on modern history has thus been a profound one. It has helped shape the conduct of international affairs from the 1790s to the Cold War: from Jefferson's declaration of US neutrality, to the ‘spectre of neutralism’ in Europe in the early 1950s, and the emergence of Third World non-alignment in the 1960s and 1970s.

The pervasiveness of neutrality in international relations has not, however, encouraged people to look upon it with affection. Machiavelli, the fifteenth-century Italian philosopher, strenuously counselled against it, warning that ‘the conqueror does not want doubtful friends [while] … the loser repudiates you because you were unwilling to go, arms in hand, and throw in your lot with him’.