As the fifth anniversary of the September 11, 2001, attacks on the United States by al-Qaida approaches, we should take the opportunity to assess the results of the response by the US and the international community. The attacks and the response to them have obviously brought about a sea change in international relations, but it would be difficult to argue that further atrocities have become less likely as a result. Why are we no more secure than we were five years ago?

Within a week of the attacks, President George W Bush declared a "war on terrorism." The metaphor of war has the singular advantage that it clearly and strongly evokes the intensity of the counterattack that was called for. Moreover, the metaphor of war constitutes an implicit appeal to intense mobilisation, not only by a country that comes under attack, but also by its friends and allies.