Just to be clear: There has never been any real evidence put forth that Russia tampered with the US elections in any direct manner. They had some bots of Facebook that attempted to sway public opinion, and that's about it. Whether they had individual agents placed as poll workers have never been proven.

My own take is that there is corruption in the US voting system and that major cities have some badly corrupted districts that could be fixed if we wanted to: Voter ID, limit absentee ballots, and place neutral observers from outside the county. It's not a matter of being able to fix the problem, it is a matter of will because voter fraud is institutional.