It has been a long road to this moment of decision on Iraq, but the inevitability of the destination has been clear. When historians have access to the memos and the diaries of the Bush administration's insiders, it's likely they will find that President Bush set his sights on removing Saddam Hussein from power soon after the 9/11 terrorist attacks -- if not before.

Everything the president has said publicly -- everything that Vice President Cheney reiterated in his Sunday television interviews -- confirms that the impact of the World Trade Center and Pentagon attacks was to steel Bush's determination to disarm any ruler who plausibly might collaborate in a similar or worse assault. And to him, disarming clearly meant dislodging that potential assailant from power.

Skeptics may argue that the United States has yet to produce convincing evidence of a link between the Baghdad regime and the al Qaeda terrorists. But the link exists in the mind of the commander in chief, and he is prepared to act on that conviction.

Looking back, the major landmarks of the past year appear to have been carefully designed to leave no alternative but war with Iraq -- or an unlikely capitulation and abdication by Hussein. Last spring the president announced -- and his security team promptly amplified -- a new doctrine that replaced the Cold War policy of containment with a policy of preemption. Bush's West Point speech and the subsequent white paper declared that the United States, with its allies, would move forcefully against any nation or force assembling weapons that could threaten our security -- and not wait passively for the attack to occur.

It quickly became clear that Iraq had been chosen as the test case of the new doctrine. In his speech to the United Nations last fall, Bush made a forceful argument that the world body needed to disarm Iraq in order to reestablish its own tattered credibility.

Subsequently the president used the pending decision of the United Nations to persuade most of the members of Congress to endorse the preemption doctrine as American policy and apply it to Iraq. And once backed by Congress, he was able to persuade the U.N. Security Council to give Hussein what amounted to a unanimous ultimatum: Disarm yourself or be disarmed.

All that was handled with considerable political skill and produced the desired results. The inspectors arrived, the buildup of military forces in the Persian Gulf began. But what was not anticipated was the scale of the opposition to preemptive war in countries that had appeared to agree with the principles Bush had enunciated.

As a result, the United States enters this conflict with fewer allies than it had hoped -- and without the explicit sanction of the United Nations. That may not be critical in the conduct of the war, even though the denial of Turkish bases forced a change in military strategy. But it increases the risks and uncertainties of what promised in any case to be a long, difficult and dangerous reconstruction process in postwar Iraq.

The fact is that Bush has broken a lot of china even before the first shot has been fired. In retrospect, we can see that the mere announcement of the preemption doctrine posed serious challenges to the United Nations view of international law and to the comity of the NATO alliance, which rests on a mutual readiness to respond to aggression, not to launch attacks.

What we know is that the imminent prospect of preemptive war with Iraq has damaged U.S. relations with much of the world -- opening rifts with major trading partners such as France and Germany, with Russia and China, and even with neighboring Canada and Mexico. The aftereffects in the Middle East and throughout the Muslim world cannot be gauged.

This is not what Bush sought or anticipated -- any more than he anticipated, when he launched his course of large-scale tax cuts, the giant deficits that now loom for the United States, threatening the economy and vital domestic programs. The members of Congress who so willingly endorsed his Iraq policy last autumn will be debating his budget this week. It behooves them to consider the consequences carefully this time.