A few reasons why Hezbollah will probably attack Israel:

(1) They say they're going to.

(2) IDF intelligence is taking the risk seriously enough that they're already doing overflights to try to deter Hezbollah.

(3) They were already ready to start a war last week.

(4) There's only so long that Hezbollah can have Al Jazeera painting them as the heroes of the Palestinian cause without doing something about it. Hezbollah is a terrorist organization, albeit one with an well-trained army: a lot of what they accomplish is through image management and propaganda. A few more days of painting themselves into a corner and Nasrallah won't have any alternative.

(5) Iran has a significant stake in making sure that Hamas doesn't get dismantled. They control Hezbollah and might try to double down.

And now a few reasons why Hezbollah will probably stay on the sidelines:

(1) They say they're going to.

(2) Israel had already publicly changed its doctrine concerning target selection in Lebanon, officially putting all Lebanese infrastructure on the table. Nobody really paid attention because it was the post-Lebanon II IDF and everybody thought it was bluster. But given the intelligence coup that Operation Cast Lead appears to be built on: Hezbollah has to wonder just how much Israel knows about their military infrastructure and to what degree the IAF would be able to untangle it from Hezbollah's human shields.

(3) The Lebanese army - such as it is - isn't sure whether Israel's serious about all of Lebanon being in play. But they're not taking any chances: they're preventing protests from getting out of control and are monitoring the border for Hezbollah activity.

(4) Hezbollah and Syria have every incentive to wait for an Obama administration before heating up the border. In the meantime Nasrallah can whip up public support by scapegoating counties like Egypt for selling out Hamas.

(5) Iran has to calculate that Hezbollah involvement puts Iran's diplomatic position at risk, if only because they'll be forced to again stake their reputation on Hezbollah's success. They have their own a huge incentive to wait a couple of months.

So yeah - I dunno. It's the Middle East and we're talking about pathologically anti-Semitic genocidal lunatics. Tough to make predictions.

References and previously after the jump...