After WW1 we let Germany be. We got WW2 as a result so after the war we dismantled Germany (it ceased to exist as a state until NATO and the USSR created West and East Germany) and forced Japan into de facto vassalage and forced passivism so we wouldn't have a repeat. The only reason Italy got off easy was because they were an Allied Power by wars end having used Mussolini as a Pinata and defected.