After 11 days of Israel's assault on Hamas in Gaza, the IDF is poised to potentially expand its ground operations. Following the opening air strikes and the subsequent limited use of ground forces, a more substantial ground offensive, taking troops deeper into the urban areas where Hamas's fighters are largely centered, now looms. Some of the reservists called up in recent days are being trained and equipped for their missions. But this next, intensified stage has not yet been green-lighted by Israel's political leaders. Prime Minister Ehud Olmert made it clear on Tuesday that restoring long-term security to the South required not only deterring Hamas from resuming rocket fire but also seriously reducing its capacity to fire and preventing a Hizbullah-style post-war rearmament via the tunnels from Egypt. In the IDF, the sense is that "seriously reducing" Hamas's offensive capability has not yet been achieved, but there is also no particular eagerness for the much-expanded ground assault. That would seem to indicate that the current level of military engagement may continue for another day or two, but then a choice will have to be made between a rapid diplomatic resolution or an escalated military offensive. Official Israel believes that Hamas has made a series of miscalculations both before and during this confrontation: initially assuming that Israel would accept a restoration of the collapsed "cease-fire" on terms more favorable to Hamas; then assuming, after the air attack phase, that Israel would not send ground forces into Gaza; expecting overt support from the Saudis and Egyptians that has not been forthcoming; and counting on Hizbullah to open a second military front in the North. The question is whether Israel has calculated correctly about what can be achieved, and how best to achieve it, in the enormously complex theater of war that is Hamastan - where enemy gunmen operate, often indistinguishably, from the midst of the civilian population. Soldiers are facing Hamas gunmen fighting out of uniform or even, in some cases, clad in stolen IDF uniforms. The ground forces are being confronted by suicide bombers, by gunmen appearing out of tunnels. They are moving through booby-trapped buildings. Hamas gunmen are commandeering ambulances and taking children out with them to battle, according to Israeli security sources. At every moment, with every use of firepower, there is the potential for Palestinian civilian casualties. As they mourn the loss of five soldiers, IDF commanders are well aware of the mounting Palestinian civilian casualty toll. They are bitterly cognizant of the reality in which Israel is blamed internationally for every such death - ratcheting up the international protests and the international pressure for a cease-fire. This impacts Israel's leverage as it seeks acceptable terms for a halt to the fighting - no matter that it is Hamas that has deliberately located its offensive capabilities in the heart of the Gazan populace. As has been clear from the first day of Operation Cast Lead, the potential for stray Israeli fire or even deaths caused in unclear circumstances to remake the contours of this confrontation is ever-present. This has been underlined in the past two days both in the losses of soldiers killed by errant IDF fire, and in the deaths of a reported 30 Gazans at a UNRWA school on Tuesday night. A considerable proportion of international support for Israel in the Second Lebanon War was wiped out when an Israeli air strike on a building close to Katyusha launch sites in south Lebanon killed 20-plus sheltering civilians. Tuesday's deaths at the UNRWA school will similarly reduce what was already precious little world sympathy for Israel. In the case of the south Lebanon attack, which occurred before dawn, it took the IDF most of the day to produce footage showing how close the Katyusha launch sites were to the building - a delay that left Israel's spokespeople bereft of an effective explanation for the incident. In the case of Tuesday's deaths, however, the IDF quickly reported that it had come under mortar fire from the school, and that its return fire had set off secondary explosions - indicating that the area was used as a weapons store. It released a statement specifying that a "a mortar battery cell" had been operating from there, and named "Hamas operatives Imad Abu Askhar and Hassan Abu Askhar" as being among those killed in the blasts. But there is scant international readiness, amid the bloodshed, to look deeply into cause and effect. As the military confrontation grows ever more complex, so, too, does the diplomatic battlefield. Many in the defense establishment believe that preventing a resumption of Hamas arms smuggling from Egypt requires the IDF's reoccupation of the Philadelphi Corridor. But the government is prepared to consider a diplomatically formulated international mechanism, just as it is prepared to consider diplomatic solutions to its other goals. Hamas, of course, will claim victory by merely surviving. And in this confrontation, rhetoric and perception are anything but marginal.