I seem to remember (dim distant past of 50 odd years ago) the Israeli AF (certain types anyhow) bore civil registration markings. I think we (Visiting Aircraft Servicing Flight) at Akrotiri occasionally handled IAF Noratlas aircraft in a camouflage paint scheme carrying what seemed like a civil aircraft registration (4X- something). Word around the section at the time suggested this was principally to ease the process of obtaining overflight/landing permissions etc. Perhaps a similar situation ?