The FBI, NSA and CIA all agree that the Russian government tried to influence the 2016 presidential election by hacking candidates and political parties and leaking the documents they gathered. That’s disturbing. But they could have done even worse. It is entirely possible for an adversary to hack American computerized voting systems directly and select the next commander in chief.
A dedicated group of technically sophisticated individuals could steal an election by hacking voting machines in key counties in just a few states. Indeed, University of Michigan computer science professor J. Alex Halderman says that he and his students could have changed the result of the November election. Halderman et al. have hacked a lot of voting machines, and there are videos to prove it. I believe him.