It's not only all manner of international statespeople, organizations and would-be mediators who are urging Israel to call a halt to the assault on Hamas and its Gaza terror state. Many Israeli opinion-shapers, too, are applying Foreign Minister Tzipi Livni's "enough is enough" epithet in quite the opposite direction from the one she had intended. Newspaper columnists, some former senior military figures and even certain TV military commentators - notably Channel 10's Alon Ben-David - were on Monday wondering, with varying degrees of impatience, whether Israel ought now to be moving toward implementing its exit strategy, in the form of a hopefully improved de facto "cease-fire" arrangement with a bloodied, though firmly unbroken Hamas. Day One of Operation Cast Lead was marked by air strikes on Hamas symbols of power in Gaza, including training bases and military command positions. Day Two saw the bombing of the Hamas lifelines - 40 supply tunnels running from Egypt beneath the Philadelphi Corridor. Day Three included strikes on weapons factories and on weapons research labs at Gaza City's Islamic University - the manufacturers of the tools of the terror trade. But at the special Knesset session Monday, Defense Minister Ehud Barak clearly suggested that more days of conflict loom in pursuit of the declared goal of this military campaign - a return of complete, stable calm to the South. Israel, he said, was engaged in "a war to the bitter end" with Hamas. The demise of Hamas rule in Gaza is not a stated aim of the current resort to force. But within the security establishment, there is no sense that Hamas has sustained a long-term strategic blow. Its estimated 15,000-strong armed force is largely intact. So, too, is a goodly proportion of its rocket-launching capability. It was Hamas that formally ended the cease-fire, and Hamas is emphatically not issuing humbled pleas for its restoration. Although the first UN figures on Monday reported dozens of civilian fatalities in Gaza over the past three days, numerous potential targets - including weapons factories, arms stores and missile silos - have not been struck in the Israeli raids because of their proximity to civilian concentrations. Much of the Hamas military infrastructure is callously interwoven with residential areas. If Barak, Livni and Prime Minister Ehud Olmert are indeed determined to achieve a genuine "remaking of the reality" in the South - to create conditions under which Hamas not only halts rocket fire, but is deterred from seeking the capacity to restart it - even such particularly problematic Hamas military targets will not be left unscathed. In this context, it should be recalled that Barak is not only a former chief of General Staff, but also the former head of the IDF's elite Sayeret Matkal commando unit, a specialist in unexpected, pinpoint operations. The defense minister has spoken repeatedly over the past three days of an Israeli readiness to "expand and intensify" the assault on Hamas until the goals of the operation are met, and the gradual massing of ground forces at the Gaza border makes that threat palpable. But Barak has not specified how the ground forces might be utilized. Hamas has always bragged that it will be ready for the IDF when the ground operation comes. Presumably Barak, who employed considerable cunning to achieve the surprise of Saturday's initial attack, is aiming for more of the unexpected.