Egregoros

No, it's more like a weird kind of Mexican Standoff. The US has what it takes to eradicate the Iranian regime, but the US cannot hold the territory - if they try, they'll be sucked into a quagmire worse than Afghanistan, and with much higher stakes (closer to Israel, Saudi, and the Hormuz). And China and Russia will OBVIOUSLY arm the insurgency to bleed out the US.

So it's more of a staring contest.