Complex sentence: He is correct, for at that moment, the coup leaders decide on an all-out nuclear strike, some of them mistakenly believing that U. S. law requires the President to obtain Congressional approval before an American nuclear attack.
Split into simpler sentences: He is correct, for at that moment, the coup leaders decide on an all-out nuclear strike. Incredibly, some of them falsely claim that U. S. law requires the President to obtain Congressional approval before an American nuclear attack.