Contrary to what some Americans believe, Europeans have known for a long time about the evils of terrorism and the need to fight it. They know, too, that the world has become a very insecure place due to the ability of small groups of fanatics to inflict unprecedented harm upon civilization. Most also recognize that a world ruled by law-from which inequalities of power and the possibility of war have been eliminated-is an impossible dream; and that a stable, multipolar world based on the balanced rivalry and cooperation of several more or less equally powerful states is not remotely at hand. In the real world, Europeans know that the United States is much stronger in the classical sense (i.e., militarily and economically) than any rival state or coalition, and that it is the most effective force for good, today as yesterday, against totalitarian threats.

But Europeans tend to believe that the legitimacy and efficacy of American hegemony and of its war on terror depend on a more differentiated view of the world than that evinced by its current mood, which somehow combines a feeling of victimhood, vulnerability and invincibility all at the same time. A sense of moral and military superiority over the rest of the world seems to be forming as the essential basis of America's war on terror, and if it does, the legitimacy and efficacy of American hegemony will suffer. There is more to hegemony than superiority, more to power than military might, more to terrorism than Al-Qaeda or Islamic fundamentalism, more to the fight against them than "war" in the classical sense-and much more to ruling the world, dealing with its problems and fighting its dangers, than can be found in the philosophy of American unilateralism or benevolent empire.

The best introduction to understanding the difference in the attitudes of Americans and Europeans toward the war on terrorism is perhaps the formulation of the Bulgarian political scientist Ivan Krastev, who says: "The American feel they are engaged in a war, the Europeans feel they are engaged in preventing one." This is true, but only half so. Both Americans and Europeans are engaged in a war against Al-Qaeda and other terrorist organizations; the war worth preventing is a wider war of the West against the rest, a real clash of civilizations; or a war between rich and poor, North and South, center and periphery, former colonizers and former colonized; or a war of Christians, Jews (and perhaps Hindus) against Muslims. It is absolutely crucial to maintain the distinction between the organized terrorist movements that hate liberalism and modernity and thrive on ideological fanaticism and, on the other hand, the sources of their recruitment, support and the sympathy they inspire in the greater part of the Islamic and, more generally, of the underdeveloped, world-which are feelings of humiliation, oppression and exclusion. This distinction is all the more important as it is precisely the strategy of the terrorists to blur it by provoking repression on wider circles of the population that they falsely claim to represent.

It follows that any specific strategy in the war against terrorism must get away from moral absolutes and fuzzily defined abstractions. What, for example, is the criterion wherein we define terrorism as "evil"? Is it the deliberate targeting of innocent civilians? But how then were the strategic bombing raids carried out by the Allies in World War II morally distinct from the attack on the World Trade Center? Is the war against terrorism, as some recent presidential pronouncements would seem to suggest, a Holy Alliance of all Great Powers against all insurgent movements, where each ally brings his own definition of terrorism corresponding to its own national or ideological opponents (Chechens, Kashmiris, Albanians, Uighurs)? Is it a war only against global or transnational terrorists, leaving aside local movements? Do we distinguish between states and non-state movements or even individuals? Or is the campaign a defensive operation by the United States (and anyone willing to join it) against those terrorists who specifically threaten to inflict harm on it and its allies while leaving aside all others or even joining forces with them? What, in short, is the evil to be extirpated?

It is clear that American policy and public opinion now tend to neglect these distinctions and to see; the United States and those who wish it well as the incarnation of the good and those who wish them harm as the incarnation of evil. Such simple clarity is perfectly legitimate in some circumstances, just as more complicated formulations-it was legitimate to be allied with Stalin against Hitler-are perfectly legitimate in others. The truth must sometimes bend in the face of strategic necessity, whether toward simplicity or complexity. But no such bending should justify beautifying the man who perfected the destruction of Grozny; or the authors of genocide in Tibet; or the man responsible for the massacres of Sabra and Shatilla and for countless other reprisals against civilian populations.

Similar problems concern the definition of war. It is legitimate to speak metaphorically of a war against terrorism as one speaks of the war against drugs, cancer or poverty, and even to connect it to the eternal war between good and evil. But as religious writers from Reinhold Niebuhr to Michael Novak have warned, seeing ourselves as the Children of Light fighting against the Children of Darkness carries the danger of self-righteousness and hubris, and may lead us ultimately to become fanatics ourselves. One should never lose sight of Arthur Koestler's saying during the fight against communist totalitarianism: "We are defending a half-truth against a total lie."

However that may be, this never-ending conflict and this metaphysical confrontation must be sharply distinguished from the concept of war in the Western tradition, lest we fall into the trap laid by bin Laden's declaration of jihad. A war, classically, is an organized activity with a beginning and an end, and with rules concerning both the legitimate ways of waging it (jus in bello) and the legitimate causes for declaring it (jus ad bellum). Of course, our time offers many examples of undeclared and unfinished war, but this does not obviate the need for rules and standards. This is essential, too, for defining the status of combatants who must either be protected as prisoners of war or prosecuted as presumed criminals.

Of course, terrorists pose a special problem. Necessity may dictate executing them summarily in times of war. Necessity may also, in an emergency, lead to a selective disregard for legal guarantees in order to prevent an imminent crime or catastrophe (although it should never justify torture even with such thin alibis as practicing it by proxy or outside one's own territory). But the point is that the burden of proof should be on those who practice the exceptional treatment. What is deeply worrying is not that principle be breached in extreme circumstances, but that the breach should be made into a generalized doctrine, the criticism of which should then be branded as anti-American.

The same applies to the new doctrine of preemption. No reasonable person would deny that if a state has reliable information on a terrorist or on a deadly criminal act being about to be perpetrated, it should not wait for the deed to be done but should seize the suspects. Nor would many deny that a pre-emptive strike against a state that is, to the best of one's knowledge, about to attack is justified in certain circumstances. But none of this displaces a central concern of both political philosophy and modern strategy to avoid the security dilemma, the "reciprocal fear of surprise attack", the temptation or the necessity of "launch on warning" postures or of pre-emptive war. Certainly, the new American doctrine is based on a valid and urgent concern: the impossibility of deterring terrorists who welcome suicide and who offer no targets for retaliation. But, once again, to generalize out of this situation a doctrine centered around the idea of launching a unilateral first strike against any state that possesses or builds weapons of mass destruction, is suspected of helping terrorists, and hence may, one hypothetical day, facilitate the use of the former by the latter against the United States, means extending the notion of preemption to an arbitrary and open-ended "anticipatory defense." It means creating a situation of permanent or open-ended exception and insecurity-in practice, permanent war-since there will always be some terrorists and some weapons of mass destruction left, and since suspect states that have been deterred so far will themselves be tempted to pre-empt. Even conceptually, the only end in sight to such a war would be total and, so to speak, totally uncontrolled control by the United States.

This brings us to broader ambiguities that surround the notion of American hegemony or empire. There is no question that the conditions for American supremacy have grown with every conflict of the last century. Neither World War I, nor Nazism, nor Communism nor apocalyptic terrorism were invented or provoked by the United States-but in each case its role was decisive in resisting the threat to freedom and civilization. In each case, too-even the last one-it emerged more powerful and better able both to extend its influence (to new territories in Central Asia these days, for instance) and to organize the peace. But in each case daunting obstacles occluded the way of the latter task, inducing contrasting temptations toward both excessive ambition and withdrawal. Woodrow Wilson's excessively idealistic faith in abstract principles and international institutions, for example, was followed by a partial retreat to half-isolationalist unilateralism (except in economic matters). In the 1940s and 1950s, on the other hand, the United States got the balance right. It managed to establish its hegemony solidly on the three pillars of military protection, economic aid and the creation of multilateral institutions. It maintained a high degree of freedom of action, while giving its allies a feeling of belonging and participation. It neither withdrew from responsibility nor overreached, except in the tragic case of Vietnam.

Building a new order after November 1989 and, even more, after September 2001, however, is a much harder task. During the Cold War, the Soviet Union created a constraint that disciplined both America's impulse toward withdrawal and excessive ambition. Today the very nature of the threat encourages both temptations. Anarchy and civil war in faraway lands encourage the reluctance to intervene; decentralized fanatical terrorism encourages the temptation to pre-empt. The prospect of "needing" to reform the political culture of nearly the entire Islamic world demoralizes some, energizes others toward nation-building.

The international scene as a whole, too, has become more complex and more difficult to control; other actors have emerged, making it more difficult for the United States either to withdraw from the world or to control its economic and political institutions: reciprocity becomes inevitable and the cost of ignoring it increases. Last, but not least, global issues involving security, the environment or world health increasingly call for multilateral cooperation and institution-building. While the use of force cannot be left to multilateral institutions or to coalitions of the willing, the prevention and resolution of conflicts cannot be left to the unilateral actions of one power, even a benign one.

We are thus left with a structural problem of the international security order-but the American administration seems not to credit the problem at all. It tends toward the primacy of unilateralism and military power, a tendency that surely will harm the legitimacy and the long-term stability of American leadership. What seems to stand in the way of the acceptability of American hegemony, in this respect, are two kinds of exceptionalism: the imperial and the nationalist.

America's imperial exceptionalism consists of a complete asymmetry of rights and duties between the hegemon and the rest of the world, in the refusal to recognize any superior law or authority that might limit its freedom of action. The last ten years have been occupied by the debate between sovereignists and interventionists, the first claiming that the sovereignty of states was and remains the basis of international order, the second that absolute sovereignty should give way to the right of intervention in favor of human rights. The United States seems to have solved this dilemma, as far as it is concerned, by claiming for itself both absolute sovereignty and the absolute right to infringe, including by military force, into the sovereignty of others.

America's exceptionalism offers not only the grandiose face of imperial hubris, but also the narrower one of parochial national interests. Any imperial power has to balance its interests as a nation and its interests as a leader, which include the interests of the system it leads. The Bush Administration, however, seems not to have gotten the hang of this balance. It does not hesitate to abandon its free-trade gospel in favor of the interests of its steel industry or its farmers, or to undermine its own efforts against weapons of mass destruction because of the distaste of its biotech industry for international intrusion. Moreover, while the logic of empire leads ultimately to Caracalla's edict, by which the Roman emperor extended citizenship to all the subjects of his empire, the current American policy pushes to the extreme the distinction between Americans and non-Americans, between the human rights of an American citizen and of an alien, between the value of an American life and that of allied soldiers, let alone of civilian populations or of enemy combatants. This inclination has always existed in the United States-witness Congress's reluctant attitude even toward those international treaties that correspond to American ideas and ideals-but this is an inclination that should be mitigated if America is to rule by invitation and consent rather than by force alone. This is all the more so since Americans are clearly not prepared to undertake the risks and accept the costs-moral and political as well as economic-of direct rule by military occupation.

America's objective should be an international regime that combines its hegemony with respect for international law and multilateral institutions; and those can have no effective role of advice and consent if they do not contain an element of autonomous or non-American power, hence some form of multipolarity. The choice is between an attempt at authoritarian global U.S. rule tempered by anarchic resistance, on the one hand, and, on the other, hegemony tempered by law, concert and consent. What happened last September 11 did not change this choice; it has just made it clearer and more urgent.

Pierre Hassner is the author of many books and essays including Violence and Peace: From the Atomic Bomb to Ethnic Cleansing and the Chaillot Paper The United States: The Empire of Force or the Force of Empire?