Iran has been unable to exploit their position in Syria to establish forward positions on the Israeli border, but they still have southern Lebanon (and a bit of influence in Gaza, too):
While Iran has backed off from the Israeli border and spent more time and effort concealing its operations and personnel in Syria, there are still plans to “destroy Israel.” These apparently revolve around upgrading over 10,000 of the longer (50 kilometers or more) range rockets Iran has provided Hezbollah. The upgrade is mainly about adding GPS guidance systems that will allow for precision attacks on Israeli targets (especially populated areas). A mass use of these rockets could overwhelm Israeli anti-missile defenses.
With much less money to play around with under renewed sanctions and lower oil prices (on top of corruption), Iran's Syria expedition doesn't have the resources it once had.
Still, a precision rocket arsenal would change the situation dramatically for Israel. Israel could very well launch a multi-division ground raid into Lebanon to really dig out Hezbollah before Hezbollah can recover from and redeploy from the heavy casualties in their expeditionary force sent to Syria to fight for Assad.
Just mass rockets alone would in time overwhelm Israel's rocket defenses which rely on the fact that only a small fraction of dumb rockets will actually hit a target, and so have to be intercepted with an Iron Dome rocket. The vast majority could be allowed to hit harmlessly.
But with 10,000 GPS-guided rockets, Israel will quickly run out of defensive missiles. Which means that Israeli ground troops need to go in and clear out the rocket-launching sites and arsenals. And as long as they are in southern Lebanon I figure the Israelis could exploit Hezbollah's Syria diversion to go further north and really tear up Hezbollah's rear area infrastructure.
Or perhaps the Israelis think that their air and missile power has got so much better than it was in 2006 that Israel can do from the air what they failed to do in 2006 the last time Israel faced a Hezbollah rocket campaign--destroy it all from the air.
But on the other hand, I've been connecting dots pointing to an Israeli ground raid for many years now. Which at least may indicate the logic is sound even if the decision to act on the logic has not been made in Israel.
