Breach of international rules of war?

[Franek Grabowski]

Thanks Adriano
Seems strange for me, a US crew flying Canberra PR.9 (and not B-57) and requiring a native speaking navigator, but well, weird things happened then. I am wondering if they were based at Wiesbaden.
Answering your question, I am awared of such anonymous flights by Swedish Spitfires and CIA's Skytrains, Flying Fortresses and Invaders, and I suppose there were hundreds of such unmarked penetration flights not only by the mentioned aircraft/services.