Except in the event of an invasion of the United States or its Territorial possessions and attack upon its citizens residing therein, the authority of Congress to declare war shall not become effective until confirmed by a majority of all votes cast thereon in a Nation-wide referendum. Congress, when it deems a national crisis to exist, may by concurrent resolution refer the question of war or peace to the citizens of the States, the question to be voted on being, Shall the United States declare war on _________? Congress may otherwise by law provide for the enforcement of this section.
This was brought up in the 1930s, and had support of a majority of the American people.
WWII would go on as planned, because Japan invaded the Philippines, which was a territorial possession, and Hitler would subsequently declare war. But what happens in the Cold War?