Not only Russia.
I've mentioned this before that when my brother worked in telecommunications he'd also " meet and greet " clients from overseas. In the late 1970's early 80's he met a client at Heathrow airport off a flight from South Africa. Rather than the client look for a hotel my brother offered him a room at his own house to which was accepted. The visitor had been interested in touring around which my brother had obliged and one morning after breakfast off they went to the old city of Chester----------but partway there my brother had to stop the car and was violently ill. However he got back and carried on until he stopped again and the same thing happened. All this time,the visitor just sat motionless in the car and didn't offer any assistance. Brother turned the car and drove back home and collapsed in bed but not before the visitor enquired about the alarm system in the house which my brother wasn't going to tell.
This " agent " then left by taxi and brother had the doctor call. Blood was taken and an " unknown substance " was found in his bloodstream.
Nothing was ever said or reported about this as GCHQ kept it quiet. Prior to all this,brother had been to South Africa on business where he'd kitted out 10 military vehicles with the latest telephone equipment.
Brother recovered,but was never physically the same after having been very fit. Now in his 70's he has cancer which I swear was a result of whatever was " put in his breakfast " that day.