Our military is in every country where there is an embassy, if I am not mistaken. Soldiers stationed in Germany are not there to fight off any threats. There aren't nearly enough there to do so, even if there was a threat. I could be wrong, but I do believe it is also a chain of information sort of thing. They are there to fill in the guys here. Again, I could be wrong, but that is my understanding of it. Shit, we have thousands in the UK and they are our allies.
ETA: I would imagine we also keep guys and gals on hand for hunting down international war criminals.
ETA: I would imagine we also keep guys and gals on hand for hunting down international war criminals.