Russia has been doing this for a long time, for example Trotsky was assassinated in 1940 [1]. The goal is to remind the "traitors" that the punishment can come at any time and make them live in fear.

It reminds me how some religious communities go after the people who don't follow their rules even after they flee to other country [2].

[1] https://en.wikipedia.org/wiki/Leon_Trotsky#Assassination

[2] https://meduza.io/en/feature/2017/05/25/we-will-set-them-str...