The U.S. shot down a civilian Iranian airplane and killed around 200 people. The commander of the ship that did this later got promoted. This does not mean the U.S. wants to use nuclear weapons against Iran. Your points are not valid.

Can you give source on him getting a promotion?

He did not get promoted later. I was wrong. But he wasn’t fired, relieved of command or put in jail. He later received an award for his naval service. But all of this irrelevant to the point I made.

When a Soviet fighter pilot shot down a Korean jetliner the U.S. reaction to that was quite a bit different than our reaction to the Vincennes shooting down the Iranian jetliner.