How? At this point in 1991, US had already destroyed 1000s of Iraqi tanks and artillery pieces.
Right now they've destroyed... zero? Single digits? IDK.
Sending ground troops into mountains against tanks, artillery, mines and MANPADs is suicidal.
This is not even questioning the situation of where theyre gonna stage and supply.
I believe this is something that'll become more transparent in the coming days.
Don't get me wrong - the US clearly expected an uprising that they could just support from the air and the sea, via special forces operations, weapons, etc., similar to the offensive in Syria that toppled Assad. They wouldn't have to directly engage with their own ground forces, they'd just have to bomb the IRGC with drones and air strikes while local insurgents and fighters from the surrounding US vassals did the heavy lifting.
But since that didn't happen, they now have to consider alternate options for overthrowing the regime. Fighters from surrounding states are still probably the best option, but without a large-scale up rising, they'd have to plan out the actual assault and supplement the fighters with troops from the US and Israel. They'd also need to secure a landing area and supply chains. These are monumental tasks that won't be completed in a few days.
Or, the other option is to once again pull back, sign a temporary peace deal, and come back in a year with all of that worked out. But Trump surely knows the Iranians won't waste time this round. The moment they sign a peace deal, the Iranians will restart their nuclear programs and start importing weapons and platforms. It'll put a timer on when Iran could be successfully attacked next, which throws the entire campaign into uncertainty.
So my guess is, they won't let up the attacks this time unless they can either completely level Iran's military and industrial infrastructure, or there is a regime change, or Trump somehow convinces other great powers to stay out of it and not export any weapons to Iran.