When the Ruskies invaded Prague in 68, we actually mobilized a brigade, I think of the 82nd, to immediately go to Europe. We already had circa 400K troops in SE Asia. What the brass was expecting a few thousand to do to combat the Ruskies on their almost home turf was naive in my view. This current one is pure crazy.
One thing the Ruskie invasion accomplished for me was my orders to South East Asia was changed to reassignment to Conus.