Donald Macintyre: Is regime change the ultimate goal?

Israeli politicians have talked for so long about a possible large-scale invasion of Gaza to confront Hamas that it has been easy to be lulled into thinking it would never actually happen. Now that it is underway, it looks as if the timing, from Israel's perspective, could be a lot worse. And not just because of the clear winter weather in which its forces have rolled into the Strip.

Globally, for example, it has a window afforded by the last two weeks of a fundamentally supportive White House and – though this is less important – the opening of a Czech EU presidency which is hardly less so. For all the calls for an immediate ceasefire, Israel – Defence Minister Ehud Barak's brief flirtation with the idea last week excepted – clearly believes it has enough leeway from Western powers to continue expanding its operation for now.

It nevertheless carries serious risks – acknowledged yesterday by Israeli analysts across a broad political spectrum. Polling before the ground offensive, but after the air attacks began, reinforced Mr Barak's initial hesitation: while a narrow majority supported the continued air offensive, only 19 per cent were in favour of one on the ground.

Doubtless that reflects the searing experience of the 2006 Lebanon war and would be transformed if there is a clear military success with a minimum of Israeli casualties. But it is a reminder that Israeli ministers – including Mr Barak, whose poll ratings rose impressively as a result of Operation Cast Lead last week – are playing for high stakes.

According to Yossi Alpher, an eminent one-time Mossad official and former director of the Jaffee Centre for Strategic Studies, the operation is a "big gamble" which Israel could have chosen to avoid given the progress Israeli air power had already made against Hamas targets, the uncertainty over future Israeli casualties, and the lack of a clear exit strategy. "We could have ended this yesterday and declared a victory. It would have been a controversial and incomplete victory but it would certainly not have been a defeat."

Conversely he acknowledges that – for now at least – the operation appears to be sufficiently "modular" to allow a choice between withdrawal "if things begin to look bad" or, in the event of a Hamas "collapse" to "go all the way".

Which raises the question of whether Israel now has wider war aims than the military's limited, if still daunting, official goal, stated again after the ground offensive began on Saturday night, of "greatly reducing" Hamas's capacity to fire rockets at Israel. While not linking it explicitly with a ground invasion that had already started, Tzipi Livni, Foreign Minister and – at present hawkish – aspirant to the premiership in next month's election, chose on Saturday night to restate Israel's desire to remove Hamas from its control of Gaza. Mr Alpher's assessment is that Israel will "play it by ear" and adopt a "wait and see attitude" to how the many variables are played out – including how long the international community will tolerate Palestinian loss of life and the potentially devastating humanitarian cost inside Gaza – before deciding on the feasibility of the "regime change" which government spokesmen last week repeatedly eschewed as a war aim.

From a right-leaning perspective Bar Ilan University's Gerald Steinberg fully agrees about the risks of the operation. He also accepts that while the view so far has been that toppling Hamas "is a desirable outcome but not one realistically within reach – if it happens, fine". And both men agree that the Israeli public is not ready for a full-scale occupation of Gaza which would reverse the 2005 disengagement and risk major Israeli and Palestinian casualties. But Professor Steinberg believes that a prevailing majority – including Ms Livni, outgoing Prime Minister Ehud Olmert and the military chief of staff Gabi Ashkenazy – concluded there was "no choice" but to press ahead with a ground operation. He is also scathing about what he sees as the Europeans' failure to balance their complaints about a humanitarian crisis in Gaza with a viable alternative to Israel's operation, one which he believes could last a little more than two weeks – until President Obama's inauguration. This, he says, should enable Israel "to find and destroy most of the significant targets".

Those targets clearly include rocket-launching and storage sites inaccessible from the air. But Mr Alpher thinks yesterday's offensive may have yet another purpose, to strengthen Israel's leverage in negotiations on a possible international force, most likely along the Gaza-Egypt border, to halt the smuggling of weaponry by Hamas.

Such a step would be as logical an end to the war as it was in Lebanon, he says, adding: "Israel has a big problem with militant Islamic non-state actors attacking us on our borders from a sort of sovereign black hole and it doesn't really have a military or political solution of its own ... If Israel could say we got an international force which will stop Hamas re-arming that would look good."

Professor Steinberg is deeply sceptical that international military powers would risk their own forces "to save Israeli lives". But Mr Alpher insists: "In Lebanon it was part of Israel's official aims. It isn't part of the official war aims now but it is certainly part of the dialogue between Israel and the international community."