Stop looking at war and foreign policy through a lens of morality and look at the actions of states as ways to further their interests.
Take the bombings of Iranian scientists, we can all probably agree that Israel and the USA are behind that. No evidence but it does make sense. It's highly illegal to assassinate foreign nationals, but it's in Israel's interest (from their POV) that Iran does not gain the capability to build a bomb, so in Israel's mind the targeted killings of Iranian scientists is justified.
In Iran's mind it is in their best interest to get a stable nuclear program up and running since they look around, see North Korea, and realize that if they can get a bomb then the USA and other Western powers will leave them alone and it will give their government a sense of legitimacy. While from the US POV it's in OUR interest for Iran to not get a nuclear capability since that means that another theocracy survives in the ME. A non-nuclear Iran, in the mind of the US, is an Iran which is still potentially able to be the victim of a regime change through economic sanctions or other methods.
Nobody is right in international relations, it's just state-actors trying to further/protect their interests. The US has more power, hard and soft, than anyone else in the world - especially Iran - thus while it may not be morally right to fuck over the Iranian people in order to destroy their economy to hopefully institute a regime change of a regime the US put into power, it's in the US (perceived) interest to do so