@changegonnacome, USSR was in no position to help Iran in 1979 since it invaded Afghanistan in 1979. Don't forget USSR fought a border war with China in the 1970s. USSR sure as hell would not and could not help Iran - already fighting a war in Afghanistan, anticipating a possible Chinese invasion in the Far East, and now fighting the US?
If Khomeini was worried about a coup originating from the US embassy, he could have just demanded that the embassy personnel leave in 48 hours or 72 hours. Taking an embassy hostage is an act of war and had either Carter or Reagan had guts, Qum and Iranian regime would have ceased to exist.
You refer to the old Bismarck saying - nations have no permanent allies, just permanent interests. Sure, but where is the sense of creating enemies? Why turn two nuclear powers into enemies? Given Iran's interference in its neighbors affairs for 2,500 years, it can hardly object or be surprised that other countries will interfere in its affairs!
You contradict yourself. In one sentence you say that those who believe in benign intentions cease to exist, in the next sentence you state that claims death to Israel and US are rhetorical flourishes. So which is it? Using your logic, US and Israel should have each wiped Iran of the face of the earth given Iran's post 1979 behavior.
You talk about deterrence as Iranian strategy, but again, Iran's strategy is not deterrence but aggression that is guaranteed to result in massive retaliation. Neither country, to my knowledge, expressed a desire to attack Iran before Iranians fired the first shot (Embassy occupation and funding Hezbollah.). You also conveniently ignore Hezbollah and Hamas attacks on Israel, since they are the opposite of deterrence. It is one thing to keep guard dogs, it is another to sic them on your neighbor. The former deters burglars, the latter invited shooting the dogs and the owner. Irans's actions have been since 1979 been the opposite of deterrence. They have been begging for a war.