Iran tight-lipped on cause of deadly port explosion amid reports of possible presence of chemicals used to fuel missiles

[Hieronymus Phact]

5. It's all still just an assumption.

I certainly wouldn't rule out Ukraine, regardless of past behaviors of anyone else. The Iranians usually show no hesitation in blaming the great satan for all manor of things deserved and not. Ukraine has shown remarkable resourcefulness, and aggressiveness in taking it to Russia's doorstep, and i wouldn't put this past them at all.

The point is: We don't know. And limiting ones self to past enmities closes our perception of other very real possibilities of new ones. Maybe the Israelis did it on their own, maybe the Ukrainians worked with the Israelis intelligence network in Iran to get it done for their mutual interests. Maybe it was really an accident. We just don't know.
Since we don't know, It's foolish to reflexively fall back on lazy assumptions. It opens you up to being manipulated.