Considering America and Israel accomplished total air superiority over Iran in matter of days just few months ago, they're obviously pretty damn far from being untouchable.
Invading Iran would be difficult, but totally destroying IRGC and military (as long as they side with the former) wouldn't be that hard. Dropping communications equipment and weapons to Iranian opposition groups wouldn't be hard either.
Yes, but what was accomplished with the air superiority? It's not regime change. It set back the nuclear program, maybe six months. That probably won't work ad infinitum, at some point they are going to build redundant sites and hardened facilities that are resilient to bunker busters.
The IRGC and military are HUGE. This is a numbers thing, not a competence thing. Neither the US or Israel has the munitions to make a lasting dent with air power alone.
Invading Iran would be difficult, but totally destroying IRGC and military (as long as they side with the former) wouldn't be that hard. Dropping communications equipment and weapons to Iranian opposition groups wouldn't be hard either.