Will the Israelis invade Gaza? Knowing how utterly stupid Olmert and Peretz have proved to be, everthing is possible. But from a military point of view invading Gaza achieves nothing: you get some Israelis killed, you get lots of Palestinians killed, and then you withdraw and you leave Hamas even stronger than it was before. Besides, after the whopping the IDF took in South Lebanon I presume that the troops are not too eager to go into another round of urban warfare.
Grant you - Hamas is not Hezbollah, not even remotely close in fact. But still, fighting in the kind of urban ghetto terrain like Gaza is just not an appealing option. Keep in mind that there are no military valuable objectives. Sure, Hamas took over the main Fatah compounds and I bet you that the Israeli Air Force will take them out shortly, but besides that there is nothing to seize, nothing to control, nothing to destroy other than the Palestinians themselves.
Fighting against elusive combattants amidst 1.4 million people crammed into 130 square miles just makes no sense at all. Also - the Israelis need to realize that there is a real risk of a “contagion effect” to the West Bank. Not militarily - the Israelis have a tight grip on all their (illegal) internal borders - but politically. There are plenty of Hamas sympathizers inside the West Bank which are going to feel encouraged by the events in Gaza. The West Bank is not Gaza, however. Fatah has a much better control over there, the population is comparatively better off and I do not see a repeat of the Gaza scenario for a while. But in 6 months? In a year? Who knows?! This is the Middle-East and things explode really fast there. If I had to make a reccommendation to the IDF General Staff I would reccommend worrying about Lebanon, Syria, the upcoming war with Iran and not about trying to hold on unto Gaza. But with Olmert in power - who knows what these crazies might decide…
Another option is, of course, invasion by proxy: an international peacekeeping force. There are already calls for such an option. Regardless, what matters is that such a force would have to be exactly in the same position as other such forces have been in other conflict areas: either as a "guest" of Hamas, in which case it would do exactly nothing to challenge Hamas, or as an occupying force, in which case it would face the same challenges as the IDF have in the past. Simply put - a peacekeeping force in Gaza solves *nothing*. Frankly, this is yet another delusional concept dreamed up by clueless politicians.
The really amazing thing is: how did Fatah, Israel or the US not get prior warning of this? Or, if the latter two did, why did they not warn Hamas. Or was the infiltration of the US-trained Fatah fighters from Egpypt into Gaza their idea of how to prevent a Hamas takeover? Because if it was - they are mighty stupid to expect Fatah thugs to stand against Hamas fighters. The only chance to prevent what took place would have been to insert several platoon strength mobile combat groups with forward air controllers into Gaza at the main Fatah compounds and ambush Hamas.
If the Israelis and/or the Americans did have prior knowledge of what was about to take place and decided not to take any action at all - then that is again a huge failure of intelligence, but this time not a operational one, but an analytical one. Clearly no doing anything and letting Hamas take over Gaza is a huge strategic blunder the prevention of which was critical for the Imperial strategy in the Middle-East.
That did not happen, and this tells me that the famous US or Israeli intelligence screwed up - as usual, I would add.