The twenty first century has opened, as so many centuries before it, with the drum roll of war depressingly audible. The optimism of the early 1990s that world politics was being remade, and that the threat of serious conflict was receding, vanished along with the twin towers that were so much a symbol of that world, one heart-breakingly beautiful September morning in 2001. And with the return of force and war to the forefront of international politics, so come the inevitable questions; when, under what circumstances, in what manner and with what restraint, may we (whoever the we might be) use force to secure our interests, protect our families, defend our communities or our values?