Stated directly: I believe our POTUS would be complicate in a act to try to get a nuke into the US. I believe he has his aids questioning the military experts on if that was practical, if they could actually do it without detection. I believe if he thought there was a chance, he’d tell Iran or whomever to try. He also try to keep his finger prints off it via Valarie Jarrett. He was also then try to keep our military stood down. He could accomplish some of that by removing some ground, naval, and airborne detection units from the path intended to get the nuke into the country.
What he cannot overcome are the space assets and all the ground units. The nuke will be detected no matter how much he tries. The nuke will be intercepted.
What I find fascinating is that while the founding fathers tried to frame a constitution to ensure equal and separate powers, they gave the President CIC powers over the military, the most potent aspect of government tyranny. They intended the militia and the people to keep that power in check, but with the massive power of the military today that is an extremely difficult task.
To prevent nuclear use by an out of control president who has dictatorial powers over the military, the entire nuclear chain of command was written with the idea that prevention against launches without cause and to ensure use of nuclear weapons when attacked but the president refuses or is incapacitated has been employed. The President isn’t the only one with nuclear launch codes and his are not the only codes necessary to launch.