Ethics & International Affairs Volume 17.1 (Spring 2003): Roundtable: Evaluating the Preemptive Use of Force: The Slippery Slope to Preventive War [Full Text]

Mar 3, 2003

The Bush administration's arguments in favor of a preemptive doctrine rest on the view that warfare has been transformed. As Colin Powell argues, "It's a different world . . . it's a new kind of threat."1 And in several important respects, war has changed along the lines the administration suggests, although that transformation has been under way for at least the last ten to fifteen years. Unconventional adversaries prepared to wage unconventional war can conceal their movements, weapons, and immediate intentions and conduct devastating surprise attacks2. Nuclear, chemical, and biological weapons, though not widely dispersed, are more readily available than they were in the recent past. And the everyday infrastructure of the United States can be turned against it as were the planes the terrorists hijacked on September 11, 2001. Further, the administration argues that we face enemies who "reject basic human values and hate the United States and everything for which it stands."3 Although vulnerability could certainly be reduced in many ways, it is impossible to achieve complete invulnerability.

Such vulnerability and fear, the argument goes, means the United States must take the offensive. Indeed, soon after the September 11, 2001, attacks, members of the Bush administration began equating self-defense with preemption:

There is no question but that the United States of America has every right, as every country does, of self-defense, and the problem with terrorism is that there is no way to defend against the terrorists at every place and every time against every conceivable technique. Therefore, the only way to deal with the terrorist network is to take the battle to them. That is in fact what we’re doing. That is in effect self-defense of a preemptive nature.4

The character of potential threats becomes extremely important in evaluating the legitimacy of the new preemption doctrine, and thus the assertion that the United States faces rogue enemies who oppose everything about the United States must be carefully evaluated. There is certainly robust evidence to believe that al-Qaeda members desire to harm the United States and American citizens. The National Security Strategy makes a questionable leap, however, when it assumes that "rogue states" also desire to harm the United States and pose an imminent military threat. Further, the administration blurs the distinction between "rogue states" and terrorists, essentially erasing the difference between terrorists and those states in which they reside: "We make no distinction between terrorists and those who knowingly harbor or provide aid to them."5 But these distinctions do indeed make a difference.

Legitimate preemption could occur if four necessary conditions were met. First, the party contemplating preemption would have a narrow conception of the "self" to be defended in circumstances of self-defense. Preemption is not justified to protect imperial interests or assets taken in a war of aggression. Second, there would have to be strong evidence that war was inevitable and likely in the immediate future. Immediate threats are those which can be made manifest within days or weeks unless action is taken to thwart them. This requires clear intelligence showing that a potential aggressor has both the capability and the intention to do harm in the near future. Capability alone is not a justification. Third, preemption should be likely to succeed in reducing the threat. Specifically, there should be a high likelihood that the source of the military threat can be found and the damage that it was about to do can be greatly reduced or eliminated by a preemptive attack. If preemption is likely to fail, it should not be undertaken. Fourth, military force must be necessary; no other measures can have time to work or be likely to work.


On the face of it, the self-defense criteria seem clear. When our lives are threatened, we must be able to defend ourselves using force if necessary. But self-defense may have another meaning, that in which our "self" is expressed not only by mere existence, but also by a free and prosperous life. For example, even if a tyrant would allow us to live, but not under institutions of our own choosing, we may justly fight to free ourselves from political oppression. But how far do the rights of the self extend? If someone threatens our access to food, or fuel, or shelter, can we legitimately use force? Or if they allow us access to the material goods necessary for our existence, but charge such a high price that we must make a terrible choice between food and health care, or between mere existence and growth, are we justified in using force to secure access to a good that would enhance the self? When economic interests and vulnerabilities are understood to be global, and when the moral and political community of democracy and human rights are defined more broadly than ever before, the self-conception of great powers tends to enlarge. But a broad conception of self is not necessarily legitimate and neither are the values to be defended completely obvious.

For example, the U.S. definition of the self to be defended has become very broad. The administration, in its most recent Quadrennial Defense Review, defines "enduring national interests" as including "contributing to economic well-being," which entails maintaining "vitality and productivity of the global economy" and "access to key markets and strategic resources." Further, the goal of U.S. strategy, according to this document, is to maintain "preeminence."6 The National Security Strategy also fuses ambitious political and economic goals with security: "The U.S. national security strategy will be based on a distinctly American internationalism that reflects the fusion of our values and our national interests. The aim of this strategy is to help make the world not just safer but better." And "today the distinction between domestic and foreign affairs is diminishing."7

If the self is defined so broadly and threats to this greater "self" are met with military force, at what point does self-defense begin to look like aggression? As Richard Betts has argued, "When security is defined in terms broader than protecting the near-term integrity of national sovereignty and borders, the distinction between offense and defense blurs hopelessly. . . . Security can be as insatiable an appetite as acquisitiveness—there may never be enough buffers."8 The large self-conception of the United States could lead to a tendency to intervene everywhere that this greater self might conceivably be at risk of, for example, losing access to markets. Thus, a conception of the self that justifies legitimate preemption in self-defense must be narrowly confined to immediate risks to life and health within borders or to the life and health of citizens abroad.


The Bush administration is correct to emphasize the United States's vulnerability to terrorist attack. The administration also argues that the United States cannot wait for a smoking gun if it comes in the form of a mushroom cloud. There may be little or no evidence in advance of a terrorist attack using nuclear, chemical, or biological weapons. Yet, under this view, the requirement for evidence is reduced to a fear that the other has, or might someday acquire, the means for an assault. But the bar for preemption seems to be set too low in the Bush administration's National Security Strategy. How much and what kind of evidence is necessary to justify preemption? What is a credible fear that justifies preemption?

As Michael Walzer has argued persuasively in Just and Unjust Wars, simple fear cannot be the only criterion. Fear is omnipresent in the context of a terrorist campaign. And if fear was once clearly justified, when and how will we know that a threat has been significantly reduced or eliminated? The nature of fear may be that once a group has suffered a terrible surprise attack, a government and people will, justifiably, be vigilant. Indeed they may, out of fear, be aware of threats to the point of hypervigilance—seeing small threats as large, and squashing all potential threats with enormous brutality.

The threshold for credible fear is necessarily lower in the context of contemporary counterterrorism war, but the consequences of lowering the threshold may be increased instability and the premature use of force. If this is the case, if fear justifies assault, then the occasions for attack will potentially be limitless since, according to the Bush administration’s own arguments, we cannot always know with certainty what the other side has, where it might be located, or when it might be used. If one attacks on the basis of fear, or suspicion that a potential adversary may someday have the intention and capacity to harm you, then the line between preemptive and preventive war has been crossed. Again, the problem is knowing the capabilities and intentions of potential adversaries.

There is thus a fine balance to be struck. The threshold of evidence and warning cannot be too low, where simple apprehension that a potential adversary might be out there somewhere and may be acquiring the means to do the United States harm triggers the offensive use of force. This is not preemption, but paranoid aggression. We must, as stressful as this is psychologically, accept some vulnerability and uncertainty. We must also avoid the tendency to exaggerate the threat and inadvertently to heighten our own fear. For example, although nuclear weapons are more widely available than in the past, as are delivery vehicles of medium and long range, these forces are not yet in the hands of dozens of terrorists. A policy that assumes such a dangerous world is, at this historical juncture, paranoid. We must, rather than assume this is the present case or will be in the future, work to make this outcome less likely.

On the other hand, the threshold of evidence and warning for justified fear cannot be so high that those who might be about to do harm get so advanced in their preparations that they cannot be stopped or the damage limited. What is required, assuming a substantial investment in intelligence gathering, assessment, and understanding of potential advisories, is a policy that both maximizes our understanding of the capabilities and intentions of potential adversaries and minimizes our physical vulnerability. While uncertainty about intentions, capabilities, and risk can never be eliminated, it can be reduced.

Fear of possible future attack is not enough to justify preemption. Rather, aggressive intent, coupled with a capacity and plans to do immediate harm, is the threshold that may trigger justified preemptive attacks. We may judge aggressive intent if the answer to these two questions is yes: First, have potential aggressors said they want to harm us in the near future or have they harmed us in the recent past? Second, are potential adversaries moving their forces into a position to do significant harm?

While it might be tempting to assume that secrecy on the part of a potential adversary is a sure sign of aggressive intentions, secrecy may simply be a desire to prepare a deterrent force. After all, potential adversaries may feel the need to look after their own defense against their neighbors or even the United States. We cannot assume that all forces in the world are aimed offensively at the United States and that all want to broadcast their defensive preparations—especially if that means they might become the target of a preventive offensive strike by the United States.

The conduct of preemptive actions must be limited in purpose to reducing or eliminating the immediate threat. Preemptive strikes that go beyond this purpose will, reasonably, be considered aggression by the targets of such strikes. Those conducting preemptive strikes should also obey the jus in bello limits of just war theory, specifically avoiding injury to noncombatants and avoiding disproportionate damage. For example, in the case of the plans for the September 11, 2001, attacks, on these criteria—and assuming intelligence warning of preparations and clear evidence of aggressive intent—a justifiable preemptive action would have been the arrest of the hijackers of the four aircraft that were to be used as weapons. But, prior to the attacks, taking the war to Afghanistan to attack al-Qaeda camps or the Taliban could not have been justified preemption.


Foreign policies must not only be judged on grounds of legality and morality, but also on grounds of prudence. Preemption is only prudent if it is limited to clear and immediate dangers and if there are limits to its conduct—proportionality, discrimination, and limited aims. If preemption becomes a regular practice or if it becomes the cover for a preventive offensive war doctrine, the strategy then may become self-defeating as it increases instability and insecurity.

Specifically, a legitimate preemptive war requires that states identify that potential aggressors have both the capability and the intention of doing great harm to you in the immediate future. However, while capability may not be in dispute, the motives and intentions of a potential adversary may be misinterpreted. Specifically, states may mobilize in what appear to be aggressive ways because they are fearful or because they are aggressive. A preemptive doctrine which has, because of great fear and a desire to control the international environment, become a preventive war doctrine of eliminating potential threats that may materialize at some point in the future is likely to create more of both fearful and aggressive states. Some states may defensively arm because they are afraid of the preemptive-preventive state; others may arm offensively because they resent the preventive war aggressor who may have killed many innocents in its quest for total security.

In either case, whether states and groups armed because they were afraid or because they have aggressive intentions, instability is likely to grow as a preventive war doctrine creates the mutual fear of surprise attack. In the case of the U.S. preemptive-preventive war doctrine, instability is likely to increase because the doctrine is coupled with the U.S. goal of maintaining global preeminence and a military force "beyond challenge."9

Further, a preventive offensive war doctrine undermines international law and diplomacy, both of which can be useful, even to hegemonic powers. Preventive war short-circuits nonmilitary means of solving problems. If all states reacted to potential adversaries as if they faced a clear and present danger of imminent attack, security would be destabilized as tensions escalated along already tense borders and regions. Article 51 of the UN Charter would lose much of its force. In sum, a preemptive-preventive doctrine moves us closer to a state of nature than a state of international law. Moreover, while preventive war doctrines assume that today's potential rival will become tomorrow’s adversary, diplomacy or some other factor could work to change the relationship from antagonism to accommodation. As Otto von Bismarck said to Wilhelm I in 1875, "I would . . . never advise Your Majesty to declare war forthwith, simply because it appeared that our opponent would begin hostilities in the near future. One can never anticipate the ways of divine providence securely enough for that."10

One can understand why any administration would favor preemption and why some would be attracted to preventive wars if they think a preventive war could guarantee security from future attack. But the psychological reassurance promised by a preventive offensive war doctrine is at best illusory, and at worst, preventive war is a recipe for conflict. Preventive wars are imprudent because they bring wars that might not happen and increase resentment. They are also unjust because they assume perfect knowledge of an adversary’s ill intentions when such a presumption of guilt may be premature or unwarranted. Preemption can be justified, on the other hand, if it is undertaken due to an immediate threat, where there is no time for diplomacy to be attempted, and where the action is limited to reducing that threat. There is a great temptation, however, to step over the line from preemptive to preventive war, because that line is vague and because the stress of living under the threat of war is great. But that temptation should be avoided, and the stress of living in fear should be assuaged by true prevention—arms control, disarmament, negotiations, confidence-building measures, and the development of international law.


1 Colin Powell, "Perspectives: Powell Defends a First Strike as Iraq Option," interview, New York Times, September 8, 2002, sec. 1, p. 18.
2 For more on the nature of this transformation, see Neta C. Crawford, "Just War Theory and the U.S. Counterterror War," Perspectives on Politics 1 (March 2003), forthcoming.
3 "The National Security Strategy of the United States of America September 2002," p. 14; available at
4 Donald H. Rumsfeld, "Remarks at Stakeout Outside ABC TV Studio," October 28, 2001; available at
5 "National Security Strategy," p. 5.
6 Department of Defense, "Quadrennial Defense Review" (Washington, D.C.: U.S. Government Printing Office, September 30, 2001), pp. 2, 30, 62.
7 "National Security Strategy," pp. 1, 31.
8 Richard K. Betts, Surprise Attack: Lessons for Defense Planning (Washington, D.C.: Brookings Institution, 1982), pp. 14–43.
9 Department of Defense, "Quadrennial Defense Review," pp. 30, 62; and “Remarks by President George W. Bush at Graduation Exercise of the United States Military Academy, West Point, New York,” June 1, 2002; available at
10Quoted in Gordon A. Craig, The Politics of the Prussian Army, 1640–1945 (Oxford: Oxford University Press, 1955), p. 255.

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