Five years after two nuclear bombs were dropped on Japan, North Korea invaded South Korea. No deterrent there.

The next time one is used, it will virtually normalize the practice.

Leaders start wars because they think they'll win and get what they want.

How does one prevent that? I haven't even mentioned the Kellogg-Briand Pact that supposedly outlawed war in 1928. Three years later one of the signatories, Japan, invaded China. A few years later another signatory, Italy, invaded Ethiopia. In 1939 Germany invaded Poland while a fourth signatory, the USSR, attacked Poland and Finland.

The U.N. was supposed to prevent future wars through negotiation and multilateral deterrence. Didn't happen.

Sorry to sound so negative, but the belief that war in general can be abolished through good will is a triumph of hope over experience.