President Kennedy was categorical on the subject. Speaking at American University in Washington, dc on June 10, 1963, he put it this way: ‘The United States, as the world knows, will never start a war.’ Twenty years later, President Reagan concurred. ‘The defence policy of the United States’, he told Americans on March 23, 1983, ‘is based on a simple premise: the United States does not start fights. We will never be an aggressor.’ Given such authoritative (and bipartisan) assurances, how then can we explain the George W. Bush administration’s promulgation of a doctrine of preventive war at the start of the 21st century? The simple answer, of course, is that 9/11 changed everything. Deputy Secretary of State Richard Armitage articulated a feeling that was widespread among Americans after the events of September 11: ‘History starts today.’footnote1 All bets were off. So too were the gloves. Deterrence and defence no longer sufficed. As President Bush himself put it, ‘the doctrine of containment just doesn’t hold water.’ Self-protection was not good enough. In Secretary of Defense Rumsfeld’s typically crisp formulation, ‘the best, and in some cases, the only defence, is a good offence.’footnote2 This was one of those cases. In order to prevent another 9/11—or something even more nightmarish—the United States had no choice but to go permanently on the offensive. With the Bush Doctrine, Washington granted itself the authority to do just that. End of story.

But the truth is more complicated. In fact, the Bush Doctrine possesses a considerable provenance. Its gestation period coincided with the Age of Overkill—the years when authorities in Washington made nuclear-strike capacity the cornerstone of us national security policy and then, more or less as an afterthought, assessed the implications of having done so. The effort to wrestle with those implications, which turned out to be vast and troublesome, gave birth to a new tradition of strategic thought. Acknowledging the influence of its chief midwife, Albert Wohlstetter, that tradition can rightly be called the Wohlstetter School.

A filmmaker attempting a behind-the-scenes portrayal of us strategy in the nuclear age would surely give Albert Wohlstetter a place of prominence—although that place would likely be a bland faculty lounge instead of the Pentagon’s bells-and-whistles War Room. Wohlstetter was the quintessential defence intellectual. From the 1950s through the 1990s, he wielded outsized influence in policy circles, without himself ever shouldering the burdens of personal responsibility—an outsider enjoying privileged inside access. Born in New York in 1913, he was a mathematician by training, who rose to prominence while an analyst at rand, which he joined in 1951. (rand also employed his wife, the historian Roberta Wohlstetter.) In 1964, Wohlstetter joined the political science faculty at the University of Chicago. There he remained for the rest of his career, training acolytes (among them Paul Wolfowitz) and mentoring protégés (among them Richard Perle), while engaging in classified research, advising government agencies and serving on blue-ribbon commissions—in general leaving his fingerprints all over the intellectual framework of us national-security strategy.

‘Paul thinks the way Albert thinks’, Perle once remarked, referring to his friend Wolfowitz.footnote3 This comment applied equally to more than a few others who rose to positions of prominence in Washington during the latter half of the twentieth century. In national security circles, Albert’s way of thinking became pervasive. So too did the abiding theme of his work: the existing situation is bad; absent drastic action today, it is almost sure to get worse still tomorrow. To those who learned from, collaborated with, or drew inspiration from Albert Wohlstetter, therefore, any defensive posture by definition is either inadequate or soon will be. The defender forfeits the initiative, a defensive orientation too easily translating into passivity, inertia and even fatalism. In an age in which survival required constant alertness and continuing exertion to improve existing capabilities and devise new ones, to rely on defence alone as a basis for strategy was to incur great risk.

For members of the Wohlstetter School, the advent of the Bush Doctrine represented the culmination of a project that they had pursued over the course of decades. Long before the events of September 2001, ideas they had developed set the stage for the United States to embrace preventive war. For Wohlstetter’s adherents, the proactive elimination of threats—thereby transcending concepts such as containment and deterrence—had long since acquired a tantalizing allure all of its own. Well before 9/11 they had persuaded themselves that preventive war was not only desirable but also feasible. All that was needed was an opportunity to put their theories into practice. On September 11, 2001, that opportunity presented itself.