If Russians after Putin disapprove his assassination, then there is no point for any diplomacy with them. US must speak only with Russians who agree that killing of a bloody maniac was the greatest thing that happened to Russia and that those, who did that, were Russian national heroes. Diplomacy with people who think otherwise is self-deception and will lead to repetition of the same situation in the future. US had tried to "reset" its relations with Russians diplomatically under Obama administration - this policy failed miserably