Prime Minister Ehud Olmert, in the course of two weeks, has gone from throwing cold water on the idea of an international force in Lebanon to making it one of the cornerstones of his policy. On July 19, in a meeting with Israeli diplomats, Olmert said the idea of an international force was "a good headline," but that Israel's experience "shows that there is nothing behind it." "Today there is a multinational force in Lebanon, and we are seeing what they do," he said in a cynical reference to UNIFIL. "I want to be careful about this, and I think it is premature to talk about it." That was then. By contrast, in a Wednesday interview with AP, Olmert said the IDF operation would stop only after a robust international peacekeeping force was in place. "Israel will stop fighting when the international force will be present in the south of Lebanon," Olmert said. "We can't stop before because if there will not be a presence of a very effective and robust international military force, Hizbullah will be there and we will have achieved nothing." In other words, it took some 14 days for the premature to ripen fully. Olmert, however, should be careful what he wishes for. The higher the bar Israel sets for an international force - the wider the mandate, the more "robust" and "effective" it wants the force to be - the more difficult it will be to put it together, said Gidi Grinstein, head of the Tel Aviv-based Reut think tank. In addition, he said, the more that is expected of the force - the larger the force, the more it is expected to do, the wider area it is expected to patrol - the more difficult it will be to get the Lebanese government to sign on to the idea. And if the multinational force cannot be deployed, that means Israel would have to continue to do the job in south Lebanon itself. The other side of the coin is if Israel lowers its expectations, gives the international force fewer responsibilities and turns it into an enhanced version of UNIFIL, then the Lebanese government might welcome it, but it would then not be an effective buffer. "This is a moment of a very hard choice for the Israeli government, and it needs to calibrate its expectations of the international force and go for something realistic," Grinstein said. "Shooting too high politically may mean a longer lasting Israeli presence in Lebanon, which may severely compromise the political achievement of this campaign." Olmert's call for an international force rests on the assumption of very clear sequencing, on what Grinstein called synchronicity - that there will be a moment when there will be a cease-fire, after which Israel will withdraw and the international force will be introduced and establish a new regime along the northern border. "But this assumption may not hold water," Grinstein said. "And if that synchronicity is lost, which means there is a cease-fire before the introduction of an international force, in that window of time Israel will be very vulnerable militarily to guerrilla warfare." During that twilight period between a cease-fire and the arrival of an international force, Israel would have to remain in Lebanon, something that would also compromise its moral standing. "Israelâ€šs moral standing, which has been preserved because of the context of the war, and the way Hizbullah has fought the war, might be compromised if Israel is again perceived as an occupying force in Lebanon," Grinstein said. But there may be no other choice. As Deputy Chief of General Staff Maj.-Gen Moshe Kaplinsky told The Jerusalem Post on Tuesday, the IDF is prepared to remain in southern Lebanon for as long as it takes, even several months, until a multinational force takes control of the territory. But if Israel does not have realistic goals for that force, the IDF may have to stay there longer, as a force that meets all of Israel's requirements might never emerge, or might never be agreed upon by the Lebanese government.