Syria is the costliest foreign adventure. So far this year some 50,000 Iranian mercenaries have been transferred to the Syrian Army. These men still take orders (and monthly pay) from Iran but now wear Syrian uniforms and are based near the Israeli border. Most of them are in Daraa province and are not popular with the locals, many of whom have been evicted from their homes by the foreigners and are treated like civilians in an occupied country.
Neither the Turks nor the Russians are happy with the Iranian presence. I'm honestly shocked that Assad is going along. Now that Iranian mercenaries aren't desperately needed to fight rebels, he should want Iran's military presence reduced to avoid being a complete vassal state.
For a decade now I've expected Israel to go in big on the ground in Lebanon to seriously tear apart Iran's proxy force Hezbollah in order to destroy the missile arsenal threatening Israel:
I assume that any war will be a multi-division push north of the Litani that will take advantage of the fact that Hezbollah, after 2006, wrongly believes it can go toe-to-toe with Israeli troops and so will fight as light infantry rather than as insurgents. For a while, Israel will be able to really pound Hizbollah ground forces as the Israelis take over rocket-launch sites and armories with troops.
Further, I'd guess the Israelis will push rapidly into the Bekaa Valley as far as Baalbek to tear up Hezbollah's rear area to slow down rearmament after the war is over. Air strikes would take place north of that, if necessary, I'd guess.
And a good portion of Israeli mechanized forces will stand ready to deter the Syrians from jumping in. The threat to drive on Damascus should be a powerful inducement to stay quiet even if Iran wants Assad to fight to the last Arab.
The idea is that it would be a giant raid lasting months before pulling back into Israel.
My thinking on an Israeli invasion evolved to think Israel would wait for maximum damage to Hezbollah fighting for Assad. But despite Hezbollah's role peaking, Israel did not strike on the ground. Although to be fair, economic sanctions on Iran are further damaging Hezbollah.
And now Iran has moved its mercenary forces (Iran is always willing to fight Israel to the last dead Arab--or Afghan Shia) closer to Israel on the Syrian border, hoping that Syrian uniforms will shield them from Israeli air attack.
Perhaps that will deter Israeli air strikes. But Iran might simply be provoking Israel into contemplating a broader ground strike into Syria itself to go after those 50,000 Iranian proxies.
That last part of my early expectation has changed because of the Syrian civil war (becoming a multi-war as multiple foreign actors fought their own wars across Syria) that began in 2011 when the Arab Spring began. The war in Syria has wrecked the Syrian army and eliminated the need for Israel to guard against Syrian intervention. Any Israeli forces tasked with deterring the Syrian army can now be used on offense.
Will Israel launch large-scale ground operations to hammer Iranian proxy forces in Lebanon and Syria?
And will Assad secretly welcome an Israeli attack that guts Iran's proxies?
UPDATE: Or is letting Iran use Syrian sovereignty as a shield just going to get Assad's surviving supporters killed?
These [50,000] “Syrian soldiers” are paid by Iran to take orders from Iran, despite the Syrian uniform. This is demoralizing for Syrian troops and the Syrian government. If these Iranian “Syrian soldiers” attack Israel the Israelis will attack Syria, including pro-Assad cities that have so far avoided major airstrikes. This is what happens in Lebanon when Iran-backed Hezbollah goes to war with Israel.
Sucks to be Assad now. But he is alive and sitting in the palace, so he's got that going for him.