Even before THE IDF moved into Gaza in February, the Arab world was talking about a "holocaust." Anti-Semitic cartoons, comparing Israelis to Nazis, flooded the Arab press. The trigger was a slip of the tongue by Deputy Defense Minister Matan Vilnai, who warned that if Hamas did not stop rocketing Israeli civilians, it would bring a "shoa" on its people. After urgent calls for clarification from the Israeli embassies in Germany and Poland, Foreign Ministry spokesman Arye Mekel put out a statement explaining the semantics of the Hebrew word "shoah," which is used to describe the Nazi Holocaust, but which can also mean "disaster" or "catastrophe." That, Mekel explained, was what Vilnai meant: That irresponsible Hamas leadership could be disastrous for the Palestinian people. Indeed, his call was for sanity, not genocide. According to figures released by the Israeli human rights organization B'Tselem, 106 Palestinians were killed in the Israel ground action and air strikes in late February-early March. Of these, B'Tselem says, 54 were non-combatants, including 25 children. Despite the relatively high civilian toll, B'Tselem cited only three instances of possible violation of war ethics - four children killed playing football on a field from which Qassams may have been fired earlier; a brother and sister shot while watching the fighting from a window; and an infant killed in an air attack on the Palestinian Interior Ministry, which, B'Tselem claims, was not a legitimate military target. Caught between international calls for Israel to exercise more care in fighting militiamen in built-up urban areas, and cabinet ministers demanding that Israel fire back immediately at sources of rocket fire, irrespective of the likely harm to civilians, Defense Minister Ehud Barak consulted legal experts. One of them was Robbie Sabel, a Hebrew University lecturer on international law and a former legal adviser to the Foreign Ministry. In this interview with The Report, Sabel explains what can be done in self-defense against an enemy like Hamas that commits war crimes by deliberately firing at civilians from highly populated urban areas. One thing, Sabel says, is clear: Even if the enemy commits war crimes, as Hamas does, the other side, in this case Israel, is still obliged to observe all the rules of war. The Jerusalem Report: Was the IDF's late February-early March action disproportional in any way? Robbie Sabel: I don't think so. There is no arithmetical way of measuring disproportionality. It is not a matter of how many civilians were killed, but whether a reasonable military commander, given what he knew at the time, would have carried out the operation. The test is not the result, but what a reasonable commander should have foreseen. For example, if it turns out that under a military bunker there was a civilian hideout, which the commander didn't know about, the attack on the bunker would still be considered legitimate. Would the fact that Israel used only a brigade and not divisions indicate proportionality? No. Proportionality does not mean you must use less or more force. Sometimes the more force you use, the less civilian casualties there are. The criterion is whether the civilian casualties are disproportionate to the military gain. So it depends on the importance of the military target? Absolutely. For instance, if you have a military HQ in a town, and it's of vital military importance to take it out, the rules of proportionality would be different from the case of a solitary soldier sitting with his rifle in a distant village. If the target is a stockpile of rockets, a manufacturing facility or a command - although it sounds very cruel - you could argue that it's of such vital importance that relatively large numbers of civilian casualties would be proportionate to the military gain. What about artillery firing back at the sources of fire? If you use a battery of artillery to fire a large number of shells at a single military emplacement in an urban environment, you can obviously assume that there will be a disproportionate number of civilian casualties. So what can you do if someone fires a lone Qassam from within an urban area? If you can say that by silencing the rocket, you are saving your own civilian casualties, and that the enemy has deliberately placed it in an urban area, then you could define it as a legitimate target. The reverse would mean giving a very significant advantage to the other side and international law would never countenance anything so absurd. Still, if one Qassam is fired from say a school or a hospital roof, you have a problem. What about evacuating areas used to fire Qassams? One way to limit civilian casualties is to warn them. You fired at us, we are firing back, get out. That would be legitimate. What about physically forcing people to leave a war zone? If it's done to punish the civilian population it would be illegal. If it's done for military purposes, to enable you to fire back at rockets coming in from a specific area without harming civilians, it would be legitimate. Declaring areas of Gaza war zones, as Vilnai suggested, would that be legitimate? Shooting indiscriminately at those areas would be illegal. But warning civilians to get out of the danger zone is legitimate. Would that be considered fair warning, Israel unilaterally defining areas as war zones? If the enemy is in fact using the area as a war zone, yes. Could we clear areas from which they are shooting rockets of buildings and foliage? If it is a military necessity. If you blow up houses to punish civilians, it's not legal. But if you need a line of fire, it's legitimate.