This is a question of a very specific kind. It doesn't ask whether the war is legitimate under international law, or whether it is politically or militarily prudent to fight it now (or ever). It asks only if it is morally defensible: just or unjust? I leave law and strategy to other people.

Saddam's war is unjust, even though he didn't start the fighting. He is not defending his country against a conquering army; he is defending his regime, which, given its record of aggression abroad and brutal repression at home, has no moral legitimacy; and he is resisting the disarmament of his regime, which was ordered (though not enforced) by the United Nations. This is a war that he could have avoided simply by meeting the demands of the UN inspectors-or, at the end, by accepting exile for the good of his country. Admittedly, self-defense is the paradigmatic case of just war, but the "self" in question is supposed to be a collective self, not a single person or a tyrannical clique seeking desperately to hold on to power, at whatever cost to ordinary people.

America's war is unjust. Though disarming Iraq is a legitimate goal, morally and politically, it is a goal that we could almost certainly have achieved with measures short of full-scale war. I have always resisted the argument that force is a "last resort," because the idea of lastness is often, as the French demonstrated this past fall and winter, merely an excuse for postponing the use of force indefinitely. There is always something else to do before doing what comes last. But force was necessary to every aspect of the containment regime that was the only real alternative to war-and it was necessary from the beginning. The no-fly zones and the embargo required forceful action almost every day, and the inspectors were only brought back to Iraq because of a credible American threat. Force is not a matter of all or nothing, and it isn't a matter of first or last (or now or never): its use must be timely and it must be proportional. At this time, in March 2003, the threat that Iraq posed could have been met with something less than the war we are now fighting. And a war fought before its time is not a just war.

But now that we are fighting it, I hope that we win it and that the Iraqi regime collapses quickly. I will not march to stop the war while Saddam is still standing, for that would strengthen his tyranny at home and make him, once again, a threat to all his neighbors. My argument with the anti-war demonstrators hangs on the relative justice of two possible endings: an American victory or anything short of that, which Saddam could call a victory for himself. But, some of the demonstrators will ask, wouldn't the first of these vindicate the disastrous diplomacy of the Bush administration that led up to the war? Yes, it might do that, but on the other hand, the second ending would vindicate the equally disastrous diplomacy of the French, who rejected every opportunity to provide an alternative to war. And, again, it would strengthen Saddam's hand.

But even people who were against starting the war can still insist that it should be fought in accordance with the two crucial commitments undertaken by the Bush administration. First, that everything possible be done to avoid or reduce civilian casualties: this is the central requirement of jus in bello, justice in the conduct of war, which all armies in all wars are obligated to meet, whatever the moral status of the war itself. Second, that everything possible be done to ensure that the post-Saddam regime be a government of, by, and for the Iraqi people: this is the central requirement of what might be called jus post bellum--the least developed part of just war theory but obviously important these days. Democracy may be a utopian aspiration, given the history of Iraq and the foreign policy record of the US in the last half century; it certainly isn't easy to imagine realizing it. But something better than the Baath in Baghdad is easy to imagine, and we are morally bound to seek a political arrangement that accommodates the Kurds and the Shi'ites, whatever difficulties that involves.

The critique of American unilateralism should focus for now on the effort to achieve a just ending for this second Gulf war. And so should the critique of European irresponsibility. The US will need help in Iraq (as we needed and still need help in Afghanistan), and that immediately raises two questions: are we willing to ask other countries, or the UN as their representative, to play a significant role in the political and economic reconstruction of Iraq? and are France, Germany, and Russia ready to play such a role, which means to take responsibility, along with us, for a decent outcome? Those three countries were not willing to take responsibility for a serious containment regime before the war; nor were we willing to invite their participation in a regime of that sort. We were committed, too soon, to war; they were committed, all along, to appeasement. A cooperative effort to bring political decency to Iraq, and to help rebuild the country's economy, might begin to create the middle ground where multilateralism could take root.

And then we can go to work on the Bush administration's environmental record, and its opposition to the International Criminal Court, and its cancellation of the test ban treaty, and its claim to a hegemonic power beyond challenge, and….