"A group of scientists encountered a problem that the computers of the day couldn’t handle, and asked von Neumann for advice on designing a new generation of computers that was up to the task. But:

When the presentation was completed, he scribbled on a pad, stared so blankly that a RAND scientist later said he looked as if “his mind had slipped his face out of gear”, then said “Gentlemen, you do not need the computer. I have the answer.” While the scientists sat in stunned silence, Von Neumann reeled off the various steps which would provide the solution to the problem."

While some of his Manhattan Project collaborators came to regret or at least agonize over their role in inventing the Bomb, von Neumann was disinclined to waste time questioning past decisions. Instead, he goaded the government to get to work building bigger, deadlier hydrogen bombs before the Russians managed the same.

His most controversial opinion was urging an immediate pre-emptive nuclear strike on Russia. And he meant immediate - he famously said “If you say why not bomb [Russia] tomorrow, I say why not today? If you say today at five o' clock, I say why not one o' clock?”