The white house staff says nobody allowed TASS journalists inside the oval office: they were moved out as soon as the staff realized the error.
So it seems that russian state agents are able to get in the same room with the president without anyone knowing.

https://www.youtube.com/watch?v=iSW8ezOmYHs&list=PLDIVi-vBsOEyETRGoRP9y8zhyu6bHl6iK