"Mobilize" for what exactly? Israel is not invading with tanks and infantry. They are hitting them with airstrikes and saboteurs.
Their air defense is severely degraded and how they'll replace (in a timely fashion) the stuff that would need to engage fighters is an open question, they do however have things that can engage drones for what it's worth.

I'd suggest you read something like this since the author practically gloats about all the ways in which they were fucked over.
>https://www.thejc.com/opinion/how-the-mossad-infiltrated-iran-using-the-enemies-already-inside-the-gates-fo1y98gj

The author openly talks about utilizing the fractured (diverse?) nature of Iranian society and since it's sanctioned to all hell, bribery is a lot easier. Iran's problem isn't enough sandbags or enough guys willing to pick up rifles, it's infiltration of spies and reliable anti-air against one of the best air forces in the world.