If the President went insane and ordered a nuclear first strike, how could it be nullified?

Question

I've looked all over the internet for the answer to this question and I've found nothing.

If the President went insane for any reason and ordered a nuclear first strike, who would need to go along with that order and how could it be nullified? I read somewhere on this site that all the President would need to do would be to convince an official whose appointment had been confirmed by congress. In that case, a President's nuclear order could be confirmed by anyone from a supreme court justice to the secretary of veterans' affairs. That seems like a terribly inefficient system, and it doesn't strike me as true.

So basically, who are the key people that would need to go along with such an order, and if the President had obviously lost his marbles, how could his orders be nullified?

Answer 1

Any presidential order to use nuclear weapons has to be confirmed by somebody on a classified list of key personnel who have access to the President and can confirm that he not only gave the order but was rational when he did so.

Answer 2

Everyone decided not to use nuke bombs because of the radiation damage to earth xD so im sure if the president tried to use any the whole world would be after us...for example iran they don't realize that if they launch a nuke all of the countries in the world would pretty much wipe them from the face of the earth xD