Let me ask you a question.... trump has vowed that the iranians will never acquire nuclear weapons. he has thrown out the diplomatic option. The only option left to achieve this is the military option.
As for going to war, Trump wont just announce to the Americans "ok, we are going to war". Something will be engineered to justify it. The Americans have done this before.... remember when walisema Iraq has weapons of mass destruction to justify the war?
Also there was the Second Gulf Of Tonkin Incident whereby the US faked an attack on its warship by the Vietnamese to justify further commitment and engage of US forces to vietnam:
For those who dont want to read the above article, the key phrase is this:
The original American report blamed North Vietnam for both incidents, but the Pentagon Papers, the memoirs of Robert McNamara, and NSA publications from 2005 proved material misrepresentation by the US government to justify a war against Vietnam.
Its normally difficult for a democracy like the US to justify a foreign war but there are ways around that.