The Bush doctrine—spelled out in a presidential speech at West Point on June 1, 2002—was meant to obliterate the Cold War tenets of deterrence and containment and to erect, instead, an assertive policy for a new era of American primacy in a world of rogue regimes and terrorists. In the swoon of apparent triumph in Afghanistan, and bristling with warnings of war to come in Iraq, President George W. Bush told the cadets, “If we wait for threats to fully materialize, we will have waited too long … We must take the battle to the enemy, disrupt his plans, and confront the worst threats before they emerge.”

Many called the policy “preemption,” but in fact it was a policy of preventive war. It is one thing (often allowed even under international law) for nations to launch a preemptive attack if they have intelligence that a foe is about to attack them; the idea is to strike first before the other side does. But Bush was talking about going to war to prevent a hostile power from developing a weapon that might pose a threat sometime in the future. Specifically, he was talking about invading Iraq not to preempt Saddam Hussein from launching a nuclear weapon but, rather, to prevent Saddam from developing such a weapon, which he then might use or give to terrorists sometime afterward.

As it turned out, Saddam had no such weapons, nor any terrorist allies with whom to share them if he had. Bush officials may have genuinely feared a Saddam bomb, but many of them had been itching for an opportunity to topple his regime by force long before the threat of terrorism helped make their case. Back in 1998, an organization called the ­Project for a New American Century wrote President Bill Clinton a letter, asserting that his policy of containment against Iraq had been “steadily eroding” such that the United States would soon “be unable to determine … whether Iraq does or does not possess” weapons of mass destruction. Thus, “the only acceptable strategy” is to “undertake military action” to oust Saddam from power. The letter’s signatories included Donald Rumsfeld, Paul Wolfowitz, Elliott Abrams, John Bolton, and Richard ­Perle—all of whom would soon be high-ranking Bush officials.

Of course, the idea of preventive war has roots still deeper in history. From the conquests of ancient Rome to Japan’s attack on Pearl Harbor, empires have often used its logic to rationalize aggression. But rarely has the notion taken hold in a democracy. In the fifties, some columnists and Air Force generals pressed for a surprise first strike against the Soviet Union before the Kremlin built up a nuclear arsenal. But President Dwight Eisenhower, despite his rhetorical policy to “roll back” communism, firmly declined.

Even in the Bush administration, the doctrine didn’t endure much beyond the Iraq invasion that it meant, in part, to justify. The idea was discredited by the postwar discovery that Saddam had no WMD, which suggested that the doctrine itself, by its very nature, risked going to war on a hunch.

Still, preemptions didn’t die out entirely. Some senior Bush officials contemplated air strikes on North Korea to prevent Kim Jong-il from building an A-bomb. But the notion fizzled when the Joint Chiefs of Staff argued, first, that they didn’t know where all of Kim’s nuclear facilities were and, second, that he could, and probably would, retaliate by launching hundreds of artillery rockets (some armed with chemical shells) against South Korea, killing as many as a million civilians.

Finally, the Bush White House long considered mounting air strikes against Iran’s nuclear facilities but met resistance, again, from the Chiefs and, more potently, from Robert Gates, who’d replaced Rumsfeld as defense secretary after the 2006 midterm elections. Gates argued that the most successful strike would merely slow down Iran’s program, not stop it. In any case, it would likely solidify the regime’s power and unleash terror, as well as war across the Middle East. Bush backed off. And with that, the final echoes of the West Point speech evaporated into the ether.

Fred Kaplan, a senior fellow at the New America Foundation, writes the “War Stories” column for Slate.