Ok, I don't know if NATO owns rail-cars (and I am not really interested in). But a waggon with UIC-number which indicates a German one and transporting non-German soldiers, is surely not in service for the Bundeswehr. Europeean coach 63 80 99-40 126-4 passed Viersen on 17th of June 2007.
Photo ©Arnim v. Herff