content: Two things.   The most effective result of a war is not winning, but having never had one in the first place. Nukes aren't great weapons, they're awful weapons that in today's world guarantee the user's destruction as much as they do the initial victims. Breaking air superiority would be a huge blow to the US war machine and a huge gain for world peace and stability.   You're assuming that China thought the US was unaware of their development. Most things in cutting edge technology are becoming exponentially more complex meaning exponentially more heads involved in development meaning exponentially less ability to keep things secret. You're not going to stick 6 clever people in a room and crack public key encryption like we did with the Enigma. Another huge shift is that technology was at one time the domain of governments, yet now it's almost exclusively the domain of the private sector. The NSA leaks were shocking not in what was technologically being done, but in the lack of ethics of what was being done.