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

The point of using a nerve agent rather than, say, arranging a freak car accident is to let people know Russia was behind it. Russia will of course deny it for the sake of international relations, but it sends the implicit message to any would be double agents that there's nowhere to flee, no country capable of keeping them safe.