Everyone forgets the Korean war, but MacArthur begged for the use of nukes when he fucked up and gave the Chinese an excuse to get directly involved. This is especially notable because while the USSR had tested a nuke at that point, they didn't have many, and they didn't have the ability to deploy them en masse against the US directly. The US still had an effective monopoly on deploying nukes, and it still didn't use them.

Oh, and fuck MacArthur.