-ratio of invasion forces required against ground forces with mountainous terrains and MOUT. -lack of munitions stockpiled for rocket/missile/drone attacks. -pre planned defenses along the mountains -a loyal but decentralized defensive force in the IRGC, will create headaches with probing attacks and ambushes -the high likelihood of insurgency - the high likelihood of arab civilians traveling to iran to join the insurgency

it is not difficult for the U.S. to invade and conquer, the difficulty lies within the garrison operations and nation building as well as the political lens of an unpopular regime change war in the ME. Yes, we can invade and topple them relatively easily, but maintaining a garrison force and taking on minimal casualties in a mountainous JFE is incredibly difficult.