When is war just?  In the American tradition, the justice or injustice of war has turned primarily upon the circumstances immediately attending the initiation of force.  The just war is the war waged in self defense or in collective defense against an armed attack.  Conversely, the unjust war is the war initiated in circumstances other than those of self or collective defense against armed aggression.  The American view of just war has thus been characterized by a singular preoccupation with the overt act of resorting to force.  It has proceeded from the conviction that whatever a state's grievances, aggressive war is an unjust--and illegal--means for settling those grievances.  This conviction was given full expression in the Gulf War.

The restriction of just war to the war of self or collective defense against armed aggression corresponds to the twentieth-century reconstruction of the Christian doctrine of bellum justum.  In the classic version of the doctrine, the just war was a war of execution, an act of vindicative justice, taken to punish a state for a wrong done and unamended.  But the rights in defense of which states might resort to war, in the absence of satisfactory alternative means of redress, were not restricted to that of self defense.

In the twentieth-century reconstruction, however, war is no longer a means generally permitted to states for the redress of rights that have been violated.  Still less is war considered a legitimate means for changing the status quo.  Armed force remains a means permitted to states only as a measure of defense against unjust attack.  This restriction of just war rests in the main on the presumption--indeed, conviction--that war no longer serves as an apt and proportionate means for resolving international conflicts.  International law has followed a similar course.  The bellum legale, as the bellum justum, is now substantially limited to one of defense, individual or collective, against armed attack.

This far-reaching change in the right of recourse to war has not gone without dissent.   Even so, the international consensus on limiting the just cause of war to that of self or collective defense against aggression is clear.  That consensus was reaffirmed in the course of the crisis that led to war in the Persian Gulf.  A war of collective defense undertaken in response to a textbook act of aggression, the justice of its cause was apparent.

That a war is undertaken in a just cause does not thereby ensure that it must be a just war.  In the American view, there is a strong disposition to assume a necessary relationship not only between the justice of resorting to war and the purposes sought in war, but between the causes and purposes of war and the manner of waging war as well.  Moral indifference to the manner of employing force is the result of moral certainty respecting the causes of, and purposes sought in, war.  Just war doctrine teaches otherwise.  It emphasizes that even a defensive war is not of necessity a just war.  The requirements laid down by just war doctrine that the conduct of war must conform to the principles of discrimination and proportionality apply to those waging a defensive war.  The justice of war's cause does not excuse the injustice of war's conduct.  If the latter is sufficiently grave, it may morally taint a war undertaken with just cause.  Even a defensive war, then, may become an unjust war if it is marked by the deliberate attack on noncombatants or if the good secured by such war is clearly outweighed by the evil attendant upon its conduct.

If these considerations hold for a war that is clearly defensive in both cause and purpose, they are all the more relevant for a war the purposes of which go well beyond those of defense, conventionally defined.  A war that is clearly defensive in cause may be much less so in purpose.  Indeed, the same purposes and anticipations that inform a preventive war may also inform a war presumably fought in self defense.  A war the purpose of which is essentially defensive is one that leaves the power and position of the enemy substantially unchanged.  Purpose is limited to repelling the aggressor, not to destroying him.  But it may be argued that merely to repel the aggression that gave rise to self defense, rather than to remove the source of aggression, is insufficient for even strictly defensive purposes given the circumstances that continue to characterize international society.

Within civil society the state presumably assures that an aggressor once repelled will be removed.  In international society, the same assurance cannot be given to states.  An equally severe restriction of measures taken in self defense may well prove unreasonable in that it may defeat the essential purpose for which such measures are considered justified in the first place.  This familiar argument has evident merit.  Yet its acceptance carries an equally evident risk, for it is in effect a license to expand the purposes of a war begun in defense to a point where it may become very difficult to set meaningful limits on the exercise of self or collective defense.  As these purposes expand, so will the interpretation belligerents give the criterion of proportionality that serves to justify the acts taken in their name.

It is with these general admonitions in mind that we may ask: Was the Gulf War a just war in the manner in which it was waged?  Was it an apt and proportionate means?  Did the good secured by the war clearly outweigh the evil attendant upon its conduct?

The manner in which the war was waged reflected, in the first instance, the vast disparity in the means available to the two sides.  This disparity meant that the element of reciprocity was largely absent from the conflict.  The expectation that like will be returned for like has always been the most important constraint on the conduct of war.  In the Gulf War, the side possessed of enormous technological advantage could act almost without fear of enemy reprisal.

The conduct of the war also reflected the conditions placed on the use of force by a public that would not tolerate another Vietnam.  A war in the Gulf, the president accordingly promised the nation, would not be "protracted"; the American government would not permit "our troops to have their hands tied behind their backs"; there would not be "any murky ending"; nor would American forces remain "a single day" longer than was necessary to achieve the objective the administration sought.  These commitments could be honored only by a war marked by the application of force on a massive scale, with the objective of utterly overwhelming the adversary and destroying his capabilities to commit further aggression.  Merely to drive Baghdad from Kuwait, though leaving its military power intact, would not remove the danger of future aggression.  Finally, these objectives had to be achieved at a modest price in American lives--if the price of victory was substantial casualties it was likely to prove too high for a nation that until the very eve of the war remained deeply divided over the wisdom of going to war.

The war that resulted from these conditioning circumstances was one waged with extraordinary ferocity.  The cost in human lives remains obscure, in part because neither the Iraqi nor the American government has an interest in determining and publicizing these costs and in part because civilian casualties will continue to mount for some time to come, if only because the human effects of the physical destruction visited on Iraq have yet to run their course.  When the full cost in lives is finally calculated, combatant and noncombatant deaths may well number several hundred thousand.  To this grim statistic must of course be added the vast destruction of industrial plants in Iraq, a destruction undertaken partly in the name of immediate military necessity and partly in pursuit of the larger objective of eliminating Baghdad as a regional power.

These and still other costs of the war may not be lightly passed over in considering its justice.  Political and military leaders may habitually employ a peculiar moral arithmetic in calculating the costs of war--one according to which the moral total of such costs largely depends on the identity of those whose lives are being counted--but moralists are expected to assess war's costs with a measure of impartiality.  Viewed from the perspective of Washington, the moral costs of the war against Iraq appear quite modest.  Viewed from a perspective that is less discriminating, a very different judgment may be reached.  Indeed, had the total casualties in the war been roughly the same but more equally shared, it is altogether likely that this nation's judgment, political and moral, would be very different from the prevailing judgment today.

These considerations notwithstanding, did the manner in which the Gulf War was waged satisfy the requirements of discrimination and of proportionality?  Of the two requirements, the principle forbidding the direct and intentional attack on the civilian population has generally been considered the more significant.  The distinction between those who may be made the object of attack and those who may not be so made is held in bellum justum to define the essential difference between war and murder--between the permitted and the forbidden taking of human life.  It is the deliberate killing of the innocent that is always to be avoided, even as a measure of reprisal in response to similar measures of an adversary.  Indiscriminate warfare, moreover, is almost by definition total war, and total war is very difficult to reconcile with the other general principle regulating war's conduct, that of proportionality.

In the Gulf War, a considerable effort was made to avoid the direct attack on the civilian population of Iraq.  That effort appears to have been on the whole quite successful, a success made possible in part by the precision of the weapons employed to destroy targets proximate to the civilian population.  At the same time, there has been a substantial, and still growing, number of civilian deaths that are the indirect result of allied air strikes.  In bombing what were designated as military objectives, facilities were destroyed that also sustained civilian life.  The severe disabling of Iraq's electrical power grid, to cite perhaps the most prominent example, was undertaken to impede the enemy's communications.  It has also had the effect, however, of contributing to the undermining of the public health system--the electric grid forms a key part of that system, the disability of which has led to inadequate sanitation and, ultimately, to epidemics.

It may be and has been contended that these and similar effects of the bombing were beside the intention of the actors, even if they were in some measure foreseen, and that the death of and injury done to noncombatants did not constitute a means for achieving an otherwise legitimate military end.  Provided these requirements of bellum justum are satisfied, there remains only the requirement of proportionality--that the evil effects not outweigh the good effects--in order to give moral sanction to the air attacks on Iraq.  But the difficulties that have so often been raised in the past by bombing are in large measure also raised in the present case.  What is termed collateral effects may reach a point at which it becomes very difficult to consider these effects as being beside the intention of the actors.  Inevitably, there is a point where one must deduce intent from effects or consequences, the determination of that point being, in turn, dependent largely on quantitative considerations.  In practice, then, whether the death and injury done to the innocent is intended or is beside the intention of the actor is determined by the scope of this death and injury.  And even though there are no objective criteria for determining how much death and injury may be done to the innocent while still preserving the right intention, this cannot affect the judgment that there are such criteria, however difficult and uncertain their delineation.  Whether these criteria were breached in the recent war is an issue that is yet to be persuasively addressed.  

The view has nevertheless arisen that the advent of precision-guided weapons has alleviated the hitherto almost intractable issues attending efforts to reconcile the principle of discrimination with the conduct of modern warfare.  On this view, the war against Iraq foreshadows a time when the use of such weapons may no longer result in collateral damage as understood in the past.  For the destruction of military objectives may then be undertaken without any concurrent death or injury to the civilian population.  Even so, this would not of necessity mean that the requirement of discrimination had been satisfied; it might only mean that the time and manner in which noncombatants were put at mortal risk had changed.  As the Gulf War has demonstrated, provided only that military objectives are given a sufficiently broad definition, the immunity belligerents are obliged to afford noncombatants may be threatened quite as gravely as it was in earlier wars of this century.  The conclusion seems unavoidable that discrimination in war will continue to depend less on the precision of weapons, or, for that matter, on the care with which they are employed against military objectives, than on the scope and meaning that is given to military necessity (and hence to the determination of what constitutes a legitimate military objective).  If this conclusion has merit, it suggests that rather than enabling belligerents to wage clearly discriminate warfare, the principal significance of precision-guided weapons might instead be to permit belligerents to wage indiscriminate warfare while persuading themselves that they are acting in a highly discriminate manner.  The Gulf War indicated that this delusion may already have taken a firm hold.

In the end, the justice of the Gulf War must turn on the test of proportionality--the critical test for judging virtually every major aspect of the war, including whether the requirement of discrimination was met.  If the conduct of the war is considered to have satisfied the requirement of discrimination, it did so largely because it presumably met the requirement of proportionality as well.  It is because the evil represented by the death and injury of noncombatants is not deemed disproportionate to the good otherwise served by the war that the criterion of discrimination is satisfied.

The principle requiring that the values preserved through force must be proportionate to the values sacrificed through force is admittedly little more than a counsel of prudence.  It expresses the common sense of the matter.  When war becomes disproportionately destructive to the good it serves, it must be condemned.  Judgments of proportionality, and its converse, are necessarily very rough and subject to considerable uncertainty.  Still, such judgments are indispensable if war is to be regarded as a rational and moral activity.  They express what may be termed the "logic of justification" and it is quite difficult to imagine how meaningful moral discourse about war could be undertaken without them.

In the conduct of the Gulf War, the issue of proportionality also arose as a result of the huge disparity in combatant casualties suffered by the respective sides.  Is proportionality violated when a belligerent takes a multitude of the enemy's lives in order to save, or simply not to put at risk, a few of his own?  That this was done in the recent war is clear.  In doing so, military commanders invoked the plea of military necessity as justification for their actions.  Given the indeterminate character of military necessity, the appeal to it often appeared plausible.  Even so, there are surely limits, ill-defined though they may be, to the number of enemy lives that may justifiably be taken to avoid risking however small a number of one's own.  At some point, the imperious claims of military necessity must yield to the claims of humanity.  This is so even if it is conceded--a concession the moralist may make only at his peril--that although human lives are human lives, some lives are still more important than others.  That point, it would seem, is above all dependent on quantitative considerations.

Was that point exceeded in the Gulf War?  The question has only seldom been raised.  When it has, more often than not the response has been to shift the meaning of military necessity from its narrower operational sense to its broader political-strategic sense.  In the latter sense, military necessity is above all a function of the objectives sought in war, of the purposes or ends for which a war is fought, rather than simply the immediate requirements of military operations (as well as the means available to belligerents for effectively carrying out these operations).  Partiality in the conduct of war is accordingly transformed into impartiality when judged by the purposes or ends of war.  Once these purposes are endowed with great enough significance, military necessity may serve to justify behavior that is very one-sided in its human consequences.

In the Gulf War, what moral embarrassment was felt at the disproportion in casualties suffered by the respective sides was partially relieved by invoking the larger ends of the war.  Yet it was not so much the ends of the war that thus strained the principle of proportionality to a breaking point as it was the manner in which the nation and its government were determined from the outset to wage war.  That manner would likely have found the expression it did whatever the purposes given the war, for it reflected the conditions upon which public support rested.

The melancholy conclusion to which these considerations lead is not that the manner in which the war was waged made it an unjust war--there is no pretension here of weighing the evil effect of the war against the good preserved or restored by the war, beginning with Kuwait's independence as a sovereign state--but that its conduct resulted in deplorable consequences which cannot be simply shrugged off as the unfortunate though inevitable by-product of war.  These consequences must be seen as seriously tainting the conduct of the war.  Nor can it be said, in mitigation, that they were unforeseen and unintended.  Quite the contrary, to an extent greater than most wars, the consequences of this war were foreseen and intended.  Determined not to have more than the most modest casualties, intent on not getting into a quagmire, enjoying great technological advantages, and persuaded that the adversary was essentially unredeemable, the only reasonable expectation was that the kind of war would be waged that was in fact waged.  Those who led the nation into war left little doubt on this score by the statements they made prior to the war's outbreak.  The generals presiding over the strategy and conduct of the war warned Baghdad that a war, once begun, would be waged with "unprecedented ferocity" and would result in the "killing" of the Iraqi army.  The president broadened the warning to the people of Iraq for whom war, he declared, would be a "calamity."  And so it proved to be.

That the war that followed these warnings raises grave questions about its conduct is perhaps less sobering than the realization that it was virtually the only kind of war we could have waged given the outlook of the American military establishment and of the nation at large.  The disproportionality that marked the conduct of the war has deep roots, which gave to its conduct almost the character of inexorability.  The consequences of the Gulf War have given new support to the view that the circumstances in which war remains an "apt and proportionate" and, accordingly, a just means have further narrowed.

Robert W. Tucker is a contributing editor of The National Interest.