Quoting from the other thread.
It's very ballsy of Iran to blatantly escalate this. Engaging the US in an actual open conflict will only end one way: regime change. I expected proxy terrorist attacks and cyber shit.
I guess they felt they could only be pushed around for so long.
I don't expect the EU to be particularly forceful in their recriminations but it's pretty clear that the US will enter this with the lightest and most lukewarm of support, I don't think they can muster even a "Coalition of the willing" here. The targeted killing is the focal point of escalation (most people would feel so) so the USA is not on a good footing either. The election is not too far away too and while the whole "support the troops" spring will jump as usual, I think a large part of the public may view this in the perspective of a 19 years war with no end in sight (and not a new conflict) and show some fatigue for it. A change of administration might be a quick end to hostilities with Iran actually sitting at the table with a better end. Even with Trump reelected he'd be caught in a possible quagmire... And seeing how versatile he is there's no telling he might disengage at all costs down the line.
Long story short Iran might have judged now was the "less worst" time to escalate. Maybe they're betting on keeping the fight in Irak (and elsewhere than Iran) as long as possible or that they keep this below open war levels.