Out of interest, what sequence of actions by which country in particular led to the modern Iranian regime?

Iran has actually never directly killed any US citizens. This misconception arises because its allies in Lebanon have done so. But the US and Israel were occupying the bottom third of Lebanon so I would hardly call that an attack.

There was also the hostage crisis but that was done by student protestors rather than the Iranian government.

Clueless? The US has been interfering in Iran (stuff like removing democratically elected prime minister) since 1953, at least.

When has Iran attacked the USA?

It is pretty obvious that the current war was started by Israel and USA.

I somewhat understand Israel's agenda and objective, even if evil and selfish depending on the point of view (or selfish, for Netanyahu to avoid legal scrutiny while acting as prime minister).

I don't understand the USA attacking here at all. With rising prices I think Trump should pay compensation to the rest of the world for his decision here. This is now similar to the build-up to Vietnam though - I don't see Trump being able to withdraw, without looking incompetent, so he is now committed to the war, similar to why Putin can not stop his invasion of Ukraine. Two criminals, one thought.