https://allthingsnuclear.org/dwright/trump-and-the-nuclear-c...
Whether the military would actually carry out those orders when no one else has ICBMs in the air is debatable, but the president's defined role as the commander-in-chief and the sole arbiter of when to open the gates of hell on earth is not.
It's not merely debatable, it's highly debatable. People aren't just going to launch nuclear weapons willy nilly, no matter who the president is, muchless for Donald J. Trump, who few people in his administration take seriously.
Trump couldn't even get Mark Esper to deploy troops domestically. Now imagine the hurdles he'd face trying to deploy troops to another country.
It is important to remember how the US launch system actually works, though, and that it's theoretically possible he could.
Wars are the result of a series of escalations. It doesn't take a lot to knock over the first domino.
On the contrary, take what happened when Trump wanted to bomb Syria, and people basically didn't let him. Presidents, especially weak, un-respected ones like Trump, can't just do things like that.
Then there's reality. And in reality, not many people respect Trump and are willing to follow his orders. This happens constantly in the news. His own cabinet members openly work against him all the time.
Most recently consider how Mark Esper publically publicly rejected using the Insurrection Act, right over top of Trump.
Now you could say—what if we had some other president? Well, the same social rules would apply to that person as well. Even if they were incredibly charismatic and well-liked and respected, they'd need to clear many social and political hurdles before the airplanes took off.