More recently the United States was prepared to deal with acute dangers by taking pre-emptive or preventive military action against states with which we were technically at peace--Cuba and the Soviet Union in 1962 and North Korea in 1994--if diplomacy had failed to remove or contain specified dangers. The great debates in the Kennedy Administration were over whether or how to even give diplomacy a chance. But there is abundant evidence of President Kennedy's underlying resolve to remove the Soviet missiles from Cuba, one way or another, to prevent an even more dangerous nuclear crisis from arising the next month over Berlin. In 1993 and 1994 the Clinton Administration readied military options against North Korea with evident purpose, but President Clinton never had to make the final decision on what to do if his diplomatic gambit failed. Actually, Iraq is a less clear case of pre-emptive strategy than either of these historical examples, since the United States and the most concerned allies have been in a sta te of hostilities against Iraq for years. The United States and others have long been conducting constant, if mostly low-intensity, combat operations ever since Iraq conclusively broke the terms of the 1991 military truce that suspended, but never concluded, the Gulf War.

The Bush Administration's strategy is a more explicit adaptation to the new conditions of international life. That explicitness has drawn fire from some who argue that while it might be proper to hold these views, it is not wise to call attention to them. They do not reject the administration's thinking, and can themselves list many examples of real and potential cases of pre-emption. They rather accuse the administration of tactlessness.

The new strategy is somewhat provocative, but it is deliberately so. It must be provocative if it is to foster the painful worldwide debate that must occur in order to condition the international community to think hard about these new dangers, and about how the cadence of security threats has changed. Although the debate is still raging, the older habits of thought are already changing, subtly, around the world. It remains to be seen how the argument over what is and is not tactful will ultimately be settled.

In any event, the United States has not arrogated to itself some vague right to pursue and pummel anyone it dislikes, as many critics contend. The strategy document lists five criteria that must be met for a state or an organization to cast itself outside of ordinary international protection. Condoleezza Rice observed in her Wriston lecture:

[T]his approach must be treated with great caution. The number of cases in which it might be justified will always be small. It does not give a green light--to the United States or any other nation--to act first without exhausting other means, including diplomacy. Pre-emptive action does not come at the beginning of a long chain of effort. The threat must be very grave. And the risks of waiting must far outweigh the risks of action.

Moreover, the administration's focus is not just on security threats, but also on opportunities. The terrorists have no vision of the future that can assure Muslim parents that their children will lead a better life; the United States does. There are only a few states that could start a new wave of dangerous WMD proliferation, and deflecting them now may nudge history in the right direction. Failure to do so, however, may condemn millions to needless suffering and the American people to years of living in fear.

Grand Strategy and Small Realities

THE BUSH Administration has helped spur worldwide debate not only about the purposes of American power, but about the objectives of the international system as a whole. The United States is not challenging the necessity of international institutions for common action, but it is pressing other nations to decide what they want, to reconsider how to get it, and to re-evaluate old habits in light of new realities. This is an uncomfortable and necessarily disruptive process, and the U.S. government is bound to add its share of distracted stumbles to its progress. But the international agenda is already changing in positive ways.

Grand strategy usually disappoints when it is carried into action. Measured against this or that phrase, this or any administration will come up short. But it is possible to offer general direction, to set different chains of action and reaction into motion. Critics of the Bush Administration's emerging ideas must either accept the new definitions of national security presented or articulate coherent alternatives, working through the implications of present--not past--realities.

There are always too many problems. But the great powers are working together more than anyone would have considered possible half a century ago. New approaches to economic and humanitarian cooperation offer great promise. The advances in human liberty and material well-being just since 1990 have been staggering enough to encourage ambitious thoughts about what might be possible. With new understandings about the real problems the United States and its friends face together, and a flexible, pragmatic approach to achieving them, the prospects have never been better for the project of building a commonwealth of freedom.

Philip Zelikow is the White Burkett Miller Professor of History and Director of the Miller Center of Public Affairs at the University of Virginia. He contributed unofficially to the preparation of the National Security Strategy of the United States, but the views expressed in this article are solely his own.