Seriously? Tehran actively supports the Shiite side in that religious war. That is a well known national security fact. You also have a very naïve notion about what can be done with air power in taking out armored ground forces. You're talking about a massive air campaign using up millions in aircraft, ammunition, guided rickets, cruise missiles, fuel, etc. It's very easy for a ground force to spread out its units so that each tank, guided missile platform, armored vehicle would require its own separate targeting. That would also include targeting of most of their modified half ton trucks they've retrofitting with 50 caliber guns.
The fact of the matter is, the forces they have now is a direct result of the U.S. leaving all that equipment behind in the (unrealistic) hope the Iraqis would have the guts to defend what we set up for them. They didn't. Why? Because when you hand someone something they haven't really earned there is little appreciation for what they had. The Iraqis walked away from the force we left them. The whole period of time we spent supplying them with armor and training was a failed plan from the get go. Why? Because their religious war runs so deep that even their own troops had more allegiance to their religion than civil government. They have NO appreciation for what they've never had. Civil, strong, democratic civil government. You won't defend what you don't understand. They've proved that many times over. Democracy is NOT appropriate everywhere. A population has to understand such things, deeply appreciate such a concept, are willing to die for it, and belief in it overrides any competing ideology. That's simply not the case over there.
We should've let them to their own devices years ago and they'd still be fighting with swords and single shot rifles. And ISIS would have very little military power as a result.
In fact the whole thing started when the Reagan administration armed the jihadists just to fight of the russian invasion. But everywhere we stick our nose into we end up making things worse in the long run. Just like a jihadist recent said in an interview, they don't care about democracy, about diversity, about compassion and civil rights. They only care about establishing their own retrograde Islamic caliphate with strict Islam law. When asked about the fact that many people don't want to live under such conditions the response was, "who are they, why haven't they left." Completely ignoring the fact that thousands have left. I say let them form what ever form of government they want. People will eventually leave or form their own committed revolution to get rid of them. It will be their blood spilt and their money spent. It is the price of revolution. Only then will they have an appreciation for democratic rule.