To Preempt or Not to Preempt?

A Comparison between the Six-Day and Yom Kippur Wars

By: Alan Dershowitz


In both 1967 and 1973 Israel faced the decision whether to preempt an expected imminent attack or to absorb the first blow and then respond. Each decision has, with the benefit of hindsight, been criticized as wrong,1 but at the time the decisions had to be made both may well have been correct. A comparison between them affords unusual insight into the appropriate criteria for preemption in the military context.


The Six-Day War

Israel had to decide whether to attack preemptively in 1967, when Egypt, in coordination with Syria, again closed the Strait of Tiran, expelled UN peacekeepers, massed its regular army on the border and threatened a genocidal war. According to Nasser, the war was to be not over the Strait of Tiran but over Israel’s “existence,” and “The objective will be Israel’s destruction.”

Hafiz al-Assad ordered his Syrian soldiers to “strike the enemy’s [civilian] settlements, tum them into dust, pave the Arab roads with the skulls of Jews. Strike them without mercy.” He characterized the forthcoming attack on Israel as a “battle of annihilation.” Damascus Radio incited its listeners: “Arab masses, this is your day. Rush to the battlefield. . . . Let them know that we shall hang the last imperialist soldier with the entrails of the last Zionist.”2

Israel attacked preemptively, destroying the Egyptian and Syrian air forces on the ground, and went on to win a decisive victory in six days. Although it also feared an attack from Jordan, it did not act preemptively against that enemy to the east. Indeed, on the morning of June 5, 1967, it passed to Jordan through a UN envoy a message that it would not attack Jordanian forces if Jordan did not attack first. Instead it absorbed the first blows from Jordanian artillery against civilian targets in West Jerusalem and military targets near Tel Aviv and Ramat David.3 Jordanian ground forces also took control of Government House in Jerusalem, threatening Mount Scopus. Israeli authorities believed that “if [the Jordanian Army] could take Mount Scopus and encircle Jewish Jerusalem,”4 it would hold a strong military position. Israel then responded with ground and air attacks. It defeated Jordan as well, though with considerable casualties.5

Much of the world accepted the necessity of, and justification for, Israel’s preemptive attack of 1967, because Israel was seen as an underdog surrounded by hostile Arab nations threatening its destruction. Moreover, Egypt had been the first to commit a casus belli, an act of war, by denying Israeli shipping access to an international waterway and then threatening a large-scale attack by expelling UN peacekeepers, and by massing its troops on the border. The Egyptian Air Force also flew over Israel’s nuclear facility in Dimona, raising the specter of an aerial attack on Israel’s nuclear capacity.6 Nasser had earlier threatened that “the Arabs would take preemptive action” in order to stop Israel from developing nuclear weapons.7 It was Israel, however, that fired the first shot, because as Israeli Prime Minister Levi Eshkol told his cabinet, a war in which “the first five minutes will be decisive” was inevitable, and “[t]he question is who will attack the other’s airfields first.”8 The Israeli Air Force attacked the Egyptian airfields first, and Israel’s air superiority was assured. Its swift and decisive ground victory resulted in fewer civilian casualties than in any comparable modem war.9 The number of Israeli civilians and soldiers who might have been killed in an initial attack from the combined Arab armies was estimated to be quite high.10 It is not absolutely certain, however, that the Egyptians would necessarily have attacked despite their provocative actions.

In his influential book Just and Unjust Wars, Michael Walzer has noted that Nasser intended to make Israel believe that a catastrophic attack was imminent, so as to require it to call up its reserves and destroy its economy as well as its self-confidence. He cited Egyptian documents captured by Israel during the war that suggested a plan by Nasser to maintain “his army on Israel’s border without [actual] war.” This would have achieved “a great victory” because it would have kept the Strait of Tiran permanently closed to Israeli shipping and because “of the strain it would have placed on the Israeli defense system.” Walzer pointed to the “basic asymmetry in the structure of forces: [T]he Egyptians could deploy. . . .their large army of long-term regulars on the Israeli border and keep it there indefinitely; the Israelis could only counter their deployment by mobilizing reserve formations, and reservists could not be kept in uniform for very long. . . .”11 He also pointed to the failure of international diplomacy that made clear “the unwillingness of the Western powers to pressure or coerce the Egyptians. . . . Day by day, diplomatic efforts seemed only to intensify Israel’s isolation.” Finally, he cited the psychological factors: “Egypt was in the grip of a war fever, familiar enough from European history, a celebration in advance of expected victories. The Israeli mood was very different, suggesting what it means to live under the threat: rumors of coming disasters were endlessly repeated; frightened men and women raided food shops, buying up their entire stock, despite government announcements that there were ample reserves; thousands of graves were dug in the military cemeteries; Israel’s political and military leaders lived on the edge of nervous exhaustion.”12

Despite the after-the-fact uncertainty whether Egypt would actually have attacked, Walzer believed that Israeli leaders experienced “just fear” and that Egyptian leaders intended “to put it in danger.”13 Accordingly, Walzer concluded: “The Israeli first strike is, I think, a clear case of legitimate anticipation.”14

The Six-Day War ended with the capture and subsequent occupation of the West Bank, Gaza, and the Golan Heights, a situation that changed international opinion and made future preemptive actions more problematic.

Walzer is plainly correct as a matter of law. In the context of both domestic individual self-defense and international military preemption, the action must be judged by what was known and reasonably believed at the time the action was taken, not by what was later learned or even what was “objectively” true.15 By that criterion Israel’s preemptive attack was a lawful instance of anticipatory self-defense in response to a deliberate provocation and threatened attack by Egypt and Syria.


The Yom Kippur War

In 1973 Israel again faced a coordinated attack from Egypt and Syria. The intelligence concerning its enemies’ intentions was not as good as in 1967, and the threat was not perceived as so grave because of the buffer provided by the territories conquered in 1967 and because the threat was not as overt. Perhaps the knowledge, obtained in the aftermath of the Six-Day War, that Nasser may not have intended to attack in June 1967, led some to believe that Sadat did not intend to strike. Moreover, in this case Sadat intended to make Israel believe that it was not planning to attack. Nonetheless, there was a brief opportunity for a preemptive attack against the Egyptian and Syrian air forces, despite the reality that they were better protected than they had been in 1967. At 4:00 a.m. on October 6, 1973, Israeli intelligence received a report from a high-level Egyptian official who was spying for Israel that an Egyptian-Syrian attack was imminent. Several military leaders proposed preemptive action. Indeed, Israel’s Chief of Staff David Elazar “ordered the commander of the air force . . . to prepare a preemptive strike and issued a standby order to attack at 11:00 in the morning.”16 But Defense Minister Moshe Dayan “adamantly opposed a preemptive strike,” observing that “we’re in a political situation in which we can’t do what we did in 1967.”17

In the hours leading up to the Egyptian-Syrian attack, the proposal for preemption was debated in front of Israel’s prime minister, Golda Meir. The case for preemption was presented by General Elazar, who argued that it would save many lives: “Elazar entered Mrs. Meir’s office on that Saturday morning with some persuasive arguments in favor of a pre-emptive air-strike, namely, that a first strike could disrupt and retard the enemy offensive, allow Israel’s army more time to mobilize, destroy at least part of the enemy air-defense systems, and limit Israeli casualties.18

The negative case was argued by Dayan, who said that a preemptive attack by Israel would make it more difficult to secure American support if needed. He believed that the “political damage Israel would incur by striking first would be far greater, and accordingly he opposed pre-emption.”19 When the presentations were completed, “the prime minister hemmed uncertainly for a few moments but then came to a clear decision. There would be no preemptive strike. Israel might be needing American assistance soon and it was imperative that it not be blamed for starting the war. ‘If we strike first we won’t get help from anybody,’ she said.”20

At the close of the war, U.S. Secretary of State Henry Kissinger told Dayan that Israel “had been wise not to stage a preemptive strike on Yom Kippur. If it had . . . it would not have received so much as a nail from the United States.”21 Because Israel was willing to absorb the first blow, and because it suffered enormous losses—in both life and in equipment22—the United States agreed to supply it with considerable replacement armaments. Most of the American weapons arrived too late for actual use in the war, but the knowledge that they were on the way allowed the Israeli Army to use all available weapons and ammunition without fear of running out.23

The immediate military cost to Israel of having not preempted is impossible to calculate, but some experts have estimated that the number of casualties suffered by Israel—2,656 dead and 7,250 wounded—would have been considerably lower.24 During the 1967 war, fewer than 800 Israeli soldiers were killed and approximately 2,500 wounded.25 More significant, the ratios of dead and wounded between Israel and its enemies was very different in the two wars. The ratio in the Yom Kippur War was between four to one and seven to one in Israel’s favor, depending on whose figures are credited,26 whereas the ratio during the Six-Day War was “approximately 25 to 1 in Israel’s favor.”27

Military historians and analysts have studied the Israeli decision not to preempt and have concluded that the cost of not preempting was high. U.S. Air Force specialists estimated that “had the air force been permitted to pre-empt, the destruction of 90 percent of the SAM [surface-to-air missile) sites could have been accomplished in a period of three to six hours for the loss of under ten aircraft.” This would have reduced “Israeli losses on the ground” considerably: “Pre-emptive air strikes on front-line missiles and troop concentrations could certainly have been expected to disrupt the enemy offensive and its communications. Some authoritative writers have argued that the IAF [Israeli Air Force] could have delivered three thousand tons of bombs on enemy targets before the Arab attack reached full strength.”28

One reason why it is impossible to come up with precise estimates of how many lives might have been saved by a preemptive attack is that such an attack could have changed the entire course of the war, perhaps even prevented the attack by Egypt and Syria.29 This must remain highly speculative, especially with regard to the Yom Kippur War because Egypt’s goal was not to win a full-blown military victory in traditional terms but rather to restore its honor by inflicting heavy casualties on the Israeli Army and regaining some of its lost territories before a cease-fire could be imposed. That is why, despite its eventual military defeat, “for Egypt, the war was a towering accomplishment,”30 and its president, Anwar el-Sadat, the man who started the war, emerged as “the clearest victor.”31 Egypt’s “victory” in the Ramadan War (as the Yom Kippur War is called in the Arab world) is still celebrated, despite massive military losses. ·

It is precisely with regard to wars that are not subject to the usual deterrent calculi of military costs and benefits that preemption becomes an attractive option. Deterrence, at least in theory, is always a preferable way of preventing a war since it relies on the sword of Damocles’ hanging rather than dropping. However, for enemies who do not fear the sword dropping, preemption may be the only realistic option. It will probably always be a matter of degree since almost no enemy is completely oblivious to the threat of retaliation.

The calculations that went into the decisions regarding the Yom Kippur War went well beyond short-term military advantages and disadvantages. Israel would almost certainly have gained considerable short-term military benefits from a preemptive strike against Egypt and Syria.32 But the longer-term risks would have been considerable, especially in regard to its relations with its major ally, the United States.33 One important reason why the risks of preemption would have been so high for Israel was that it had successfully employed that tactic six years earlier and had won an overwhelming victory. Because it now was perceived as so strong, and because it had been criticized in some quarters for starting the shooting in the Six-Day War, Israel was in a difficult position with regard to preempting once again. It feared—understandably, as it turned out—that the international community would not believe that it was in fact acting preemptively once again to ward off an inevitable and imminent attack, but rather that it was using the excuse of preventive self-defense to wage an aggressive war.

This suggests another important potential cost of preemption: that once done—even successfully—it becomes difficult to repeat. This is so for a variety of practical reasons. First, an enemy who is aware of the prior preemptive act can better prepare for a repetition. Sadat went to great efforts to mask his intentions on the eve of the Yom Kippur War so as to deny Israel the opportunity to take effective preemptive measures. (We shall see how Israel’s preemptive attack against Iraq’s nuclear reactor in 1981 caused Iran to take precautions against a similar attack later.) Second, a successful preemptive attack makes it difficult to justify—on moral, legal, political, and diplomatic grounds—a subsequent attack. We saw this in Dayan’s argument against a repeat in 1973 of what Israel had done successfully in 1967. Finally, and related to the second reason, if a nation repeatedly preempts following an initial successful preemption, the propriety of its initial preemption will be retrospectively challenged. This too was part of Dayan’s concerns. We shall see that the United States’ preventive attack on Iraq in 2003 (and its subsequent occupation) have made it more difficult to justify a preventive attack against Iran’s nuclear facilities, even though Iran appears to be much closer to developing nuclear weapons than Iraq was.

Another related factor that may have contributed to Israel’s decisions to preempt in 1967 but not in 1973 is that in 1967 Nasser was overtly threatening to attack and took action designed to make Israel, and the world, believe that an attack was imminent (even if it was not). The world would thus be more likely to accept Israel’s preemptive justification than it would in 1973, when Sadat intended that Israel, and the world, believe that he was not planning an attack (even though he was). Accordingly, a preemptive attack may be more acceptable in the face of an overt threat, even if intended as a bluff, than in the face of a well-concealed sneak attack.

In sum, therefore, an analysis of the Six-Day and Yom Kippur wars suggests that a major factor in deciding whether to undertake a preemptive attack will generally be the short-term military advantage secured by striking the first blow. As Shimon Peres, the former prime minister and defense minister of Israel, has written, it is the duty of a leader to “meet [war] under the least dangerous conditions,” which necessarily must include the option of a preemptive attack.34 But there will be other considerations as well, including political, diplomatic, legal, moral, humanitarian, and prudential. Moreover, there is always the possibility that firing the first shot—even on the basis of the best intelligence and with the highest of motives—may turn out to provoke a war that would not otherwise have begun.

The burden of justification should always be on the nation that acts preemptively or preventively. In satisfying that burden, the anticipatory actor can point to the certainty of an attack, its imminence, and the extent of the damage it would suffer from absorbing the first blow, both militarily and to its civilian population. Other critical factors include the nature of the preemptive action (a single decisive first strike against a military target as distinguished from a full-scale war with massive casualties and a long-term occupation); the limited damage to noncombatants it would inflict with its preemption (especially as compared with absorbing the first blow and then retaliating); the likelihood of a shorter, less damaging war, if it preempts; and other ineffable factors. In the end the decision will always be dependent on the quality of intelligence and an assessment of probabilities.35 It will also turn on the comparative values placed on the lives of a nation’s own civilians and soldiers and those of its enemies. It will always be a matter of degree and judgment. But no law or rule of morality will ever succeed in prohibiting all preemptive military actions. Nor should it.36


Alan M. Dershowitz, Preemption: A Knife that Cuts Both Ways (New York: W.W. Norton, 2007).

Reprinted with permission from publisher.



  1. See pp. 82–83, 85.
  2. Quoted in Dershowitz, The Case for Israel, loc. cit., p. 92.
  3. Michael B. Oren, Six Days of War: June 1967 and the Making of the Modern Middle East (Oxford, U.K.: Oxford University Press, 2002), pp. 186–87
  4. Samir A. Mutawi, Jordan in the 1967 War (Cambridge, U.K.: Cambridge University Press, 1987), p. 124.
  5. See Oren, op. cit., pp. 305–06.
  6. Warner D. Farr, “The Third Temple’s Holy of Holies: Israel’s Nuclear Weapons,” Counterproliferation Papers, Future Warfare Series No. 2; accessible at http://www.
  7. Michael Karpin, The Bomb in the Basement (New York: Simon & Schuster, 2006), p. 276 (of uncorrected proofs).
  8. Oren, op. cit., p. 82. Some have argued with the benefit of hindsight, that it is possible that absent Israel’s first strike, there would have been no 1967 war. Even if that were true, and it is impossible to be certain that it is, Israel’s actions must be judged on the basis of what it knew and reasonably believed at the time. As prime minister of Israel Menachem Begin spoke about the uncertainty Israel faced and its motives in launching its preemptive strike: “In June 1967, we again had a choice. The Egyptian Army concentrations in the Sinai approaches do not prove that Nasser was really about to attack us. We must be honest with ourselves. We decided to attack him. This was a war of self-defense in the noblest sense of the term. The Government of National Unity then established and decided unanimously: we will take the initiative and attack the enemy, drive him back, and thus assure the security of Israel and the future of the nation.”—“Excerpts from Begin Speech at National Defense College,” New York Times, August 21, 1982, p. 6.
  9. See Oren, op. cit., p. 306: “Casualty rates . . . among civilians was remarkably low [because] much of the fighting took place far from major population centers.”
  10. , pp. 162–64
  11. Michael Walzer, Just and Unjust Wars (New York: Basic Books, 2000), pp. 83–86.
  12. , p. 84.
  13. See also Eric Hammel, Six Days in June: How Israel Won the 1967 Arab-Israeli War (Pacifica, Calif.: Pacifica Press, 2001), p. 29: “[T]he bluff. . . Nasser commenced on May 13, 1967 ensured that the inevitable war would commence sooner rather than later.”
  14. See, for example, Washington v. Hazlett, 113 N.W. (1907), pp. 371, 380–81; and Washington v. Wanrow, 88 Wash. 2d 221, 559 P.2d (1977), p. 548.
  15. Steven J. Rosen and Martin Indyk, “The Temptation to Pre-empt in a Fifth Arab-Israeli War,” Orbis (Summer 1976), p. 270.
  16. Abraham Rabinovich, The Yom Kippur War: The Epic Encounter That Transformed the Middle East (New York NY: Knopf Doubleday Publishing Group, 1967), p. 87
  17. Rosen and Indyk, op. cit., p. 272.
  18. , p. 273. Even in the planning stages for a possible war, preemption was essentially taken of the table:

In the wake of the 1967 victory new elements were introduced into Israel’s calculus. The capture of Sinai, the West Bank, and the Golan Heights for the first time provided her with strategic depth and with what her leaders regarded as defensible borders. Thus it was believe that preemption was no longer a military necessity. Moreover, the political costs of preemption had risen considerably, as America sought stability in the region as a precondition for a negotiated settlement. Accordingly, Defense Minister Dayan ordered the IDF to rely primarily on a non-preemptive strategy. Instead, the Israeli forces depended on early warning of any Arab intention to attack to allow time for mobilization.

—Ibid., p. 270.

  1. Rabinovich, op. cit. p. 89.
  2. , p. 454. Some have questioned this assessment. See p. 304, n.50.
  3. There were times during the Yom Kippur War when Moshe Dayan and other feared for the survival of Israel. Abraham Rabinovich wrote: “What [Dayan] sensed now as Israel’s mortality and it shook him. He was gripped, he would later write, by an anxiety he had never before known.”—Ibid., p. 218.
  4. , p. 491.
  5. To put the losses into comparative perspective, Israel “lost almost three times as many men per capita in nineteen days as the United States in Vietnam in close to a decade.” Ibid., p. 498.
  6. Many of Israeli casualties of the 1967 war occurred on the Jordanian front, and they might have been avoided or reduced had Israel taken preemptive action against Jordan.
  7. “Arab casualties as given by a western analyst were 8,528 dead and 19,450 wounded. Israel estimated Arab casualties to be almost twice those figures—15,000 dead . . . and 35,000 wounded . . .” Rabinovich, op. cit., p. 497.
  8. Oren, op. cit., p. 305.
  9. Rosen and Indyk, op. cit., p. 272.
  10. It might also have prevented the subsequent peace treaty between Egypt and Israel—or perhaps facilitated it. No one can know for certain. The contingencies of history, especially military history, always leave much to speculation.
  11. Rabinovich, op. cit., p. 55.
  12. , p. 507. At least in short term. He was assassinated several years later by Islamic fundamentalists.
  13. The issue is complicated by the fact that Israel did not even call up all its reserve soldiers in the days leading up to the Yom Kippur attack, as it did in 1967. General Elazar estimated that “if we had mobilized, the war would have lasted three, four, six days.”—Ibid., p. 489.

Mobilization, especially by Israel, which relies on reserved, can itself be viewed as a preemptive tactic—or at least as a combination of preemption and deterrence.

  1. It turned out, ironically, that “[a]t the initial meeting of the policy makers [in Washington at the beginning of the war], most participants presumed that Israel had started the war”—probably because of its preemptive actions in 1967.—Ibid., p. 322.

This and other factors have led some experts to conclude that Meir was wrong to refuse preemption because of fear of American reaction. “Two influential exponents of this line of reasoning, Edward Luttwak and Water Laqueur, have denigrated the political costs of preemption in arguing: ‘. . . the moral issue of who fired first did not after all make any difference. Rather the reverse. Most governments blandly accused the Israelis of being aggressors. Clearly only the United States mattered, and it remains an open question whether an Israeli air strike against Arab forces whose offensive have entered the operational phase would have made much of a difference to American opinion.’”—Rosen and Indyk, op. cit., p. 275.

  1. Shimon Peres, From These Men: Seven Founders of the State of Israel (New York: Wyndham, 1979), p. 55; quoted in William C. Bradford, “The Duty to Defend Them: A Natural Law Justification for the Bush Doctrine of Preventive War,” Notre Dame Law Review, vol. 79 (2004), p. 1457.
  2. For an interesting analysis of how an “abundance of information” may have led Israel “to intelligence hubris,” see Efraim Halevy, “In Defense of the Intelligence Services,” Economist, July 29, 2004.
  3. Walzer sought to revise the preexisting paradigm in light of his conclusion justifying Israeli preemption in the Six-Day War:

To say that [Israel’s preemption was justified], however, is to suggest a major revision of the legalist paradigm. For it means that aggression can be made out not only in the absence of any immediate intention to launch such an attack or invasion. The general formula must go something like this: states may use military force in the threats of war, whenever the failure to do would seriously risk their territorial integrity or political independence. Under such circumstances it can fairly be said that they have been forced to fight and that they are victims of aggression. Since there are no police upon whom they can call, the moment at which states are forced to fight probably comes sooner than it would for individuals in a settled domestic society. But if we imagine an unstable society, like the “wild-west” of American fiction, the analogy can be restated: a state under threat is like an individual hunted by an enemy who has announced his intension of killing or injuring him. Surely such a person may surprise his hunter, if he is able to do so. The formula is permissive, but it implies restrictions that can usefully be unpacked only with reference to particular cases. It is obvious, for example, that measures short of war are preferable to war itself whenever they hold out the hope of similar or nearly similar effectiveness. But what those measures might be, or how long they must be tried, cannot be a matter of priori stipulation. In the case of the Six-Day war, the “asymmetry in the structure of forces” set a time limit on diplomatic efforts that would have no relevance to conflicts involving other sorts of states and armies. A general rule containing words like “seriously” opens a broad path for human judgement—which it is, no doubt, the purpose of the legalist paradigm to narrow or block altogether. But it is a fact of our moral life that political leaders make such judgements, and that once they are made the rest of us uniformly condemn them. Rather, we weigh and evaluate their actions on the basis of criteria like those I have tried to describe. When we do that we are acknowledging that there are threats with which no nation can be expected to live. And that acknowledgement is an important part of our understanding aggression. —Walzer, op. cit., p. 85.