Is the US ripe for a coup?

[Anomalocaris]

And when the president decides to launch a nuke at them?

Traditionally, US presidents have been discouraged from owning their own WMDs. It's considered more pragmatic to let the military keep them.

Us president has the final and unchallengeable authority to use the country’s nuclear weapons.

But presumably the country that saw fit to trust such a burden to its chief executive and commander in chief of its armed forces, and which was great enough to survive and win, for the time being, the Cold War, could not have been the same one that could have made trump its chief executive and commander in chief of its armed forces.