Prof. Michael Walzer, professor emeritus at the Institute of Advanced Study in Princeton, New Jersey, is considered one of the world's leading experts on the rules of warfare. His book "Just and Unjust Wars: A Moral Argument with Historical Illustrations," has greatly influenced this field of study. Walzer, an American Jew, was in Israel this week to address two conferences: "Democracies and the Right of Self-Defense," at Bar-Ilan University's Begin-Sadat Center for Strategic Studies at Bar Ilan University, and a conference on armies and law at the Interdisciplinary Center Herzliya. Walzer has also taken part in the internal debate in Israel regarding the nature of combat required of the Israel Defense Forces against terror, which developed mainly in the wake of Operation Cast Lead.

Prof. Walzer, in Israel the killing of Osama bin Laden is seen as a belated justification for the policy of assassinations adopted by the IDF against leaders of terror organizations in the territories and in Lebanon in the past decade. On the other hand, when Israel adopts methods similar to those being used today by the United States, it becomes the target of severe criticism worldwide.

Open gallery view Walzer in Jerusalem. “I think that killing bin Laden was a legitimate act of war, but I don’t like it when it’s called justice.” Credit: Tomer Appelbaum

"In Europe there is also criticism of the United States in the wake of the killing of bin Laden. In effect, the United States has been involved in targeted killings for a long time, in Afghanistan, Pakistan and Yemen. This is somewhat more spectacular, but it's the same thing. I think that killing bin Laden was a legitimate act of war, but I don't like it when it's called justice. We're at war with Al-Qaida - and bin Laden is a legitimate target. We would have brought him to justice had he been hiding in Paris rather than Pakistan. In such a case we could have arrested him, tried him and granted him the rights made possible by a democratic legal system. But Afghanistan and Pakistan are war zones. When there is a clear distinction between the military and political leadership of an organization, as was the case with the Sinn Fein and the Irish Republican Army in Northern Ireland, there is no reason to cause physical harm to the political leadership. But if the political leadership uses this title as a cover for its involvement in terror, striking at it is legitimate."

And still, about two years ago you wrote a critical article in Haaretz about the thesis of Prof. Asa Kasher and Maj. Gen. Amos Yadlin, which the IDF adopted to a certain extent in its conduct in Operation Cast Lead. But Kasher and Yadlin also claimed that there is no similarity between terror in the Gaza Strip and the arrest of a suspect in East Jerusalem, which implies that there is no reason to make exaggerated accusations against IDF soldiers when they are fighting terrorists who use civilians as human shields in Gaza.

"When, about 10 years ago, the United States bombed from the air a van in Yemen carrying Al-Qaida members, I wrote that had the van been on a street in Philadelphia we wouldn't have been able to attack it by firing a missile. The rules of the game in a peaceful region differ from those in a war zone. When the target can be stopped without any need to fight in order to reach him, we're talking about a peaceful region and you act as you would against a criminal, not against an enemy."

In Israel the philosophers continue to argue, and the army is in no rush to decide between these approaches. Do you think the IDF needs a manual for asymmetric warfare?

"Every army needs defined rules for warfare. It's not an issue that is unique to the IDF. It was a central issue for the U.S. Army, and Gen. Stanley McChrystal did in fact publish a combat manual, a set of rules of engagement, for Afghanistan. The rules require the army to minimize the risks it imposes on civilians. In the United States, too, the rules aroused protests by soldiers in the field. No matter how clear you make them there will always be an opening for interpretation here - and the critical level for interpretation will be the junior officers in the field. There will always be different interpretations in different combat units. That's what's happening in Afghanistan and I heard that it also happened during IDF combat in Gaza."

You claim that in effect an army cannot be satisfied with not intending to harm enemy civilians, but must intend not to harm civilians. What is the significance of this distinction?

"It's a distinction I made after the Vietnam War. I think the test lies in the question whether positive steps were taken to limit the harm to civilians. Prof. Kasher also says that there is a need to warn enemy civilians before beginning an attack on military targets in their vicinity, but I think that publicizing a warning to civilians is not sufficient. In Vietnam we created free fire zones. We called on civilians to leave, and after that the soldiers had the right to shoot there freely. The problem is that in actuality, many residents don't leave. The elderly, the sick, people caring for the elderly and the sick, anyone who is afraid that his property will be looted or anyone who has nowhere to go. We killed a large number of civilians in the free fire zones - and that's one of the reasons why we lost the battle for the hearts and minds of the Vietnamese population. Something similar is happening in Afghanistan, and I assume wherever there is asymmetric warfare. I believe that even after you have issued a warning, you still have to take into account those who remain in the war zone."

What did you think of the article by Judge Richard Goldstone in The Washington Post expressing regret for some of the claims of his commission investigating Operation Cast Lead?

"There's a crucial mistake for which Goldstone didn't apologize. That is his committee's refusal to take into account the difficulties involved in asymmetric warfare and to discuss them seriously. How do you deal with an enemy who uses a civilian population as a human shield? The Goldstone Report didn't discuss that at all, and that is its great failure. The members of the commission write like lawyers, not like people who are trying to analyze the reality."

Do you think there's a need for a fundamental change in the rules of warfare in order to suit them to fighting terror?

"The basic principles of a just war must apply even in such a situation. In targeted killing it is still important that the target be legitimate and that the collateral damage be reduced to the absolute minimum. The basic principles are similar: It is necessary to distinguish between combatants and noncombatants and to act so as to minimize the death and injury of noncombatants ('collateral damage' ). The tough question is whether civilians who are being used as human shields must be treated differently. But the term 'human shield' tells only half the story. The terrorists also use civilians in order to expose them - because they believe (and they are right ) that civilian deaths caused by the opposing army will help the struggle of the terror organization. So that's a good reason to shield the shields as best you can."

In the IDF in recent years there has been increased support for bombing strategic infrastructure facilities as part of the pressure on the enemy during combat. Is that a legitimate method?

"That's a question that also came up in the United States. In the 1991 Gulf War, power plants and water purification facilities [in Iraq] were bombed. Causing inconvenience to civilians in order to apply pressure on the regime to surrender is a legitimate step. But when you damage purification facilities, for example, you are liable to cause a cholera epidemic among civilians, so that kind of warfare is not consistent with our moral standards and our commitment to decency in combat, and therefore I opposed it in '91 and would oppose it at any time. Attacking government buildings is another matter, for example in Lebanon, when Hezbollah is now part of the government."

The Israeli leadership is concerned about the campaign of delegitimization being conducted against the state, particularly in universities abroad. Are you seeing significant anti-Israel activity on U.S. campuses?

"The situation is much worse on Western European campuses, in England in particular. In Princeton a Palestinian group recently tried to remove Sabra-brand hummus products from the cafeterias, claiming that the company has adopted an IDF unit. The student council brought up the issue for a campus-wide vote and the initiative was rejected by a large majority. That's a comical example, but it does suggest that there are opportunities for Israel and considerable empathy on American campuses. The greatest empathy exists, of course, on the campuses of military schools such as West Point or [the United States Naval Academy in] Annapolis. There they see a similarity between the warfare being conducted by Israel and the American struggle in Afghanistan. But you definitely have a political problem: Most of the world does not believe (with good reason ) that you're committed to withdrawal from the occupied territories and to the two-state solution. If there were a change in the policy of the Israeli government, a strong indication of a commitment to withdraw, it would be much easier to defend Israel against delegitimization campaigns. It's a battle that can be won, certainly on the American campuses with which I'm familiar."