I don’t know the answer for sure, but 25 years ago when I flew from Dover Airforce base and landed in Germany at Rhein Main Air base (my dad was military and we caught a space A flight for a vacation) they did not check our passports at all. We just landed, collected our luggage and left the base right into Germany. It might be different now. We had our passports with us, I don’t think they were checked even when we came back to the states, but in the states they made us go through customs. We didn’t have anything to claim so we walked right though, some other people had some food or alcohol maybe, I am not sure. Basically, my military ID was my ID into America.