Sounds like Reforger. That exercise (similar to this) was done annually in the 70's and 80's. It was stopped in 1991.
Return of Forces to Germany. Used to be training for a Soviet invasion, I think. Mostly on the old East German border. Grafenwoehr was the staging area, IIRC.
The question is, why is this being restarted? Grenell being upgraded to temp head of DNI and restarting the maneuvers is a pretty big statement thrown in Germany's direction. Germans are going to go postal over this. Not that it matters.