The four years separating NATO's intervention in Kosovo from the American-ledinvasion of Iraq in the spring of 2003 were eventful ones indeed for the UnitedStates, marking as they did the emergence of a new global strategic environmentin the wake of the terrorist attacks on New York and Washington on September 11,2001. The strategic stakes for the United States and its allies in the Balkanswere marginal, and the Clinton administration as a whole would prove a reluctantwarrior in committing American prestige and resources in a war of“choice” waged overridingly for humanitarian purposes. The eventsof 9/11 represented the first time United States territory had beenattacked since Pearl Harbor, and deeply shocked the nation. The administrationof George W. Bush quickly realized that a new enemy had appeared on theinternational stage in the form of radical Islamism, a fanatical and elusiveenemy that posed a threat of unknowable but potentially grave damage to theAmerican homeland and required a fundamental rethinking of American nationalsecurity policy. The administration acknowledged that these attacks were in factacts of “war,” not simply acts of terrorist criminality, and thatthe United States would have to take this war to its source, rather than simplyattempting to defend itself against this new foe. Quite unlike the conflicts thenation had been involved in since the end of the Cold War, this “globalwar on terror” would be a war not of “choice” but of“necessity.”

Much would remain uncertain about the nature and intentions of the foe, but9/11 did seem to establish some clarifying certainties. Sympathy for theUnited States around the world was virtually universal, and for the first timesince its founding, NATO declared its readiness to help defend one of itsmembers under the terms of Article V of the North Atlantic Treaty. It wasgenerally accepted that terrorism could no longer be treated as a nuisance to bedealt with primarily by the tools of law enforcement, but needed to be seen as athreat of global reach and potentially of mass destructiveness, to be addressedby all means up to and including the military instrument.