The reaction was predictable and very much understandable from a human psychology perspective. So in my mind the responsibility for the strait being closed rests mostly with the US.
> The president is fine, btw. It was the "supreme leader" that got killed
In Iran the supreme leader is the head of state. In the US it's the president.
> he is known to have ordered the extermination of 600,000 Syrian muslims
Do you mean the Syrian civil war? According to Wikipedia it's 650,000 deaths on all sides together (more than half being combatants). I'm not sure it's fair to attribute all these deaths to Iran. By the way these numbers are similar to those of the Iraq War of GWB.