Another early device problem was the threat model post WWII is of course nations will put up a near Manhattan Project level of effort which turns out to be just

Another early device problem was the threat model post WWII is of course nations will put up a near Manhattan Project level of effort which turns out to be just enough to break it, everyone knows that. Pre WWII of course, they figured if a PHD mathematician couldn't crack it in a couple hours with chalk and chalkboard, well, surely they'll just give up, right? The ratio of optimism to pessimism was a bit off.