Since he is clearly incapable of defeating Hamas with his own meagre forces, the officials say, "Israel must be prepared to do the job on his behalf".

At the same time, influential right-wing politicians in Israel's shaky coalition government are publicly pressing prime minister Ehud Olmert to stop Hamas rocket attacks from Gaza once and for all. But with memories of the disastrous invasion of South Lebanon last summer still fresh in the minds of Israel's military commanders, nobody expects Hamas to be a pushover.

According to Israeli intelligence sources, since Israel pulled out of Gaza two years ago, Hamas has been methodically building up its military muscle, transforming its tough street-fighters into a disciplined force capable of deploying in battalion, even brigade, strength - with a reserve of special forces as back-up.

Israeli insiders predict that large numbers of reservists will have to be mobilised to create a sufficient spearhead for the planned incursion. Yet the 2006 conflict with Lebanon demonstrated glaring weaknesses in the

training and equipment of Israel's part-time soldiers. Hand-to-hand fighting in Gaza's teeming refugee camps could result in heavy civilian casualties - hardly the ideal launch-pad for a revived peace process.

Meanwhile, one veteran Palestinian observer points out that for Mahmoud Abbas to be returned to power in Gaza "on the back of an Israeli tank" would be hugely damaging for him politically. By contrast, heroic resistance from Hamas, whether it is ultimately defeated or not, would bolster the militants' standing in the Palestinian 'street', where optimism about what the Annapolis accords will really deliver is hard to find.

As for Olmert, he returns home to a personally awkward announcement. After a lengthy investigation, police are to say today whether the PM should be indicted on corruption charges.