In the quarter-century since this book first appeared, there have been few moments of uncertainty as to the direction of international relations and international law to compare with the early years of the twenty-first century. Globalisation has brought undoubted benefits in the fields of commerce, technology and communications, but also increased dangers concerning the rapid spread of disease and the growth of international terrorism. The clearly understood rules and limitations as to state conduct apparent during the Cold War period have disappeared and (for the moment at least) the optimism engendered by a renewed United Nations in the early 1990s has dissipated. Increasing resort to force by states, entities and individuals coupled with the apparently easy access to weapons of high destructive capacity pose a significant challenge to those wishing to establish a world order based on justice, mutual respect, toleration and forbearance.

Certain key events must be noted, for they have combined to shift the orientation of international relations. Increasing human rights violations committed in the Kosovo province of Yugoslavia in 1998–9 precipitated an air attack by NATO undertaken not in self-defence nor pursuant to a United Nations mandate but rather on explicit humanitarian grounds. Even more dramatically, the attack on the US on 11 September 2001 has jolted easy conceptions of international behaviour and has led, not only to significant diplomatic activity to deal with the phenomenon of international terrorism in all its forms, but also to the use of force in an effort to punish, discourage and pre-empt such activity.