Jakey:
It was, more accurately an act of war.
You could make that argument if you could show that it was deliberate. For all the noise you've made here, that is one of the more intelligent things you've posted: the Iranian government could have characterized that incident as an act of war.
More technically, it could be termed
casus belli.
Strangely enough, the Iranians didn't follow through, even though our political relations at the time were abysmal.
Any idea why that might be?