The Mullahs in Tehran have have few actual allies, in its region or the world.
Both China and Russia are friends of convenience and are not going to back an Iranian WWIII Jihad against the U.S.
Iran will not initiate a conventional arms attack on U.S. military bases, knowing the “conventional” response from the U.S. will be massive.
Iran will use its internationalized proxy, its Quds Force, in one or more kinds of attacks its uncoventional Quds Force is used to. The U.S. will hit the sources and the planners of any such attacks.
It will be tit for tat for some period of time, not WWIII.
Iran is in a really vulnerable position right now, and will be for several weeks or months.
The President is not using the old rules, so Iranian deniability is now denied.