It could be extremely widespread if it is used by intelligence agencies, especially if the attacks are conducted by official embassy staff with diplomatic immun

It could be extremely widespread if it is used by intelligence agencies, especially if the attacks are conducted by official embassy staff with diplomatic immunity abroad or by domestic intelligence operatives in the country. For example, I don't think CIA operatives could easily snatch a car full of FSB agents on the streets of Moscow, confiscate their equipment, and get away with it. The same for Havana. (If they had a way to detect the attacks, they might try, but the point is even then it wouldn't be easy. AFAIK, operatives generally do not attack each other directly on foreign soil.)