melbye said:
I don't know, but if they want to assassinate Russians living in other countries maybe don't be so obvious about it

^ being obvious about it was the point.
Its to send a message to their own intelligence officers, saying you cant defect, or tell secrets or eventually we ll get you.

Russia is more than capable of doing such a "hit" without it in any way leading back to them.
Just as the USA is,... and probably does from time to time.