“Sounds like Israel First.”
Carpet bombing by American B-52s first
....
Israeli commandos
....
It's an asymmetric war.
The IRGC doesn't care what you do to the denizens of Tehran, Mashhad, Isfahan, etc. You can nuke them for all they care. They recently murdered 53,000 of them themselves for the crime of protesting against them in the streets.
The vast majority of IRGC don't live in the cities. They are scattered around in hundreds of wack-a-mole subterranean military bases throughout the 320,000 square miles of Iran's mountain terrain. The mountainous area alone is 1.2 times the size of Texas.
Merely keeping the strait of Hormuz shut down cripples the global economy, and all they have to do to accomplish it is ocassionally launch a drone or missile at a ship from any of their hundreds of remote bases. The quantity of fertilizer for next year's crops has already been crippled by the shut down. What do you think happens next, when there isn't enough fertilizer?
In an asymmetric war, time is on the side of the asymmetric guy. The longer the war drags on, the more global damage is done and the more the United States is hated for making it happen. And they can drag it on for a long, long time.
Good luck with your plans for military conquest, General.
PS - Israel won't sending any cannon fodder to Iran. They tricked us into doing it for them.