However, as you mentioned about Russia, "It was a failure of intelligence and assessment", isn't the same true for the US?

No. Russia never had accurate information about Ukraine, and it appears that a lot of the information that it did have about Ukraine and its own operational deficiencies never made it to Putin. Because reporting information about defects in Russian capabilities would have been a career-ending move.

But in the U.S., Trump would have had all that information available to him. The military operations went like clockwork, so we had excellent intel and information about both our capabilities and those of the Iranians.

Putin made a bad choice in part because he was operating with bad intelligence data and a lack of information. Trump just made a bad choice. We won't know the details of his decision-making until many years from now (if ever - Trump notoriously hates record-keeping, and is likely to want to take what records do exist with him), so we can only speculate. But the most likely thing is that he just went with his gut feeling about what would happen in Iran if we blew up their leadership and bombed them like crazy, it was the wrong call.