But had the US not been part of the first strike, they could have applied much more diplomatic pressure to open the strait. As an active aggressor, they have no wiggle room. It might seem like semantics to you, but there's a huge difference diplomatically.
Pressure from most of the world isn't enough, why would additional pressure from the US (who Iran already regarded as an enemy) have made the difference?
Iran didn't really do anything last year after supposedly having their facilities "totally annihilated". But it used to be that the US was respected enough that public saber rattling and behind the scenes diplomatic efforts would avoid conflict. Sadly, we've done our damnedest to turn that respect into a joke. We used to make deals with people, but the greatest deal maker ripped up all of them and replaced them with nothing on the word better deals were for the taking.