There is probably no particular goal. It's just how they do things, how they exert power. Active measures [1] and all that. Fear of being poisoned keeps people loyal. Disinformation and propaganda don't let dissent spread, influence politics, etc.

[1] https://en.wikipedia.org/wiki/Active_measures

1. Provide just enough of an argument to allow sympathetic people in their own population to believe they are not monsters.

2. But make the argument weak enough that everyone else knows they are monsters, and can and will kill any opponents.

None of this requires the weird song and dance with the Putin interview 'suggestion', the interview on RT hours afterwards, etc. It's probably not particularly fruitful to treat and try to interpret this as some kind of deeply subtle hyperdimensional chess.

I really have no idea, it's far too bizarre to fit any kind of obvious explanation. State-sponsored trolling, perhaps.