THe US can simply nuke supply lines and oil refineries especially to force the USSR to give up. Nuclear war in 1951 is not the end of the USSR as a nation but it WILL be defeated.
So the USSR won't retaliate if Korea and China are tactically nuked. As others have said, it makes the USA look like terrible warmongers, and sort of legitimatizes the future tactical use of atomic weapons. I think that MAD would still be in effect (just like in WW2 nobody used poison gas or anthrax against each other), but proxy wars would become much more deadly, and possibly more frequent if it is found that they can be "won" through the use of nuclear bombs.
Nuclear proliferation happens. If Israel gets nukes and can use them against armies in the field the UAR sure as hell won't let them be the only ones.
Basically, a more dangerous world.
So the USSR won't retaliate if Korea and China are tactically nuked. As others have said, it makes the USA look like terrible warmongers, and sort of legitimatizes the future tactical use of atomic weapons. I think that MAD would still be in effect (just like in WW2 nobody used poison gas or anthrax against each other), but proxy wars would become much more deadly, and possibly more frequent if it is found that they can be "won" through the use of nuclear bombs.
Nuclear proliferation happens. If Israel gets nukes and can use them against armies in the field the UAR sure as hell won't let them be the only ones.
Basically, a more dangerous world.