And will his generals follow his orders? There will be at least some who would not implement "the red button" option.
I read an interesting article recently (
https://www.vox.com/world/2017/11/17/16656856/trump-congress-nuclear-weapons-war) that said the participation of the rest of the chain of command would depend on whether it was the generals going to the president to request an attack, or if it was the president going to the generals to request an attack. The article outlined two scenarios:
1. There's an incoming nuclear attack detected by US early warning systems. The military would inform the president, present options, and he'd have a few minutes to confer with his national security team and make a decision. This is the scenario contemplated for most of the cold war.
In this scenario there wouldn't be much dissent from the military if the president ordered a nuclear strike, because it would be the military offering the nuclear option in retaliation for a nuclear attack, which would fit in with existing policy regarding the use of nuclear weapons. Plus, there wouldn't be a lot of time for discussion, as the incoming missiles would arrive in about 30 minutes.
2. The second scenario is if the president gets mad at something somebody said on Twitter (or something else equally stupid) and calls up the military and says he wants to initiate a nuclear attack.
In this scenario, without the time pressure of an incoming attack or any other military threat to the US, it's thought that the national security team and the generals at the Pentagon would ask a lot of questions and try to reign in the president's stupidity. It's under this scenario, too, that the article envisioned a lot of people resigning rather than carrying out the orders to start a nuclear war.