“I’m not sure how carrying out assassinations in other countries for revenge purposes would benefit Putin politically”
This isn’t revenge or political. It was punishment for treason.
“Russian leaders seem to go out of their way to get rid of anybody that seems to be in their way, someone who’s betrayed them, someone who’s interrupting the money flow, and they don’t seem to care about borders. They just go wherever they have to go to get their guy,” said Joe Serio, the American author of “Investigating the Russian Mafia,” who spent nearly ten years with the anti-organized crime unit of Moscow’s police
http://www.businessinsider.com/russia-uses-us-uk-to-target-kill-former-spies-putin-enemies-2018-3