Tactical nukes might be quite useful against massed infantry storming over the border twixt North and South Korea.
Exactly. My thought is taht when we take out the reprocessing plant we make it clear that any NK attack will be met with overwhelming force, perhaps including nukes. This is because they have threatened us with Nukes, and because they can do so much damage to SK in a short time. Also, we don't want to be bogged down in a major Asian land war. We might also need the nukes to take out their missile factories/ nuke plants hidden in mountains.
Having said this, I doubt we will do it. Fallout from NK goes right across Japan. Also, SK would be affected.