I see what you mean, but I suspect the author might be referring to the Russian disinformation campaign to favour Republicans. I see it just as an example - obviously it can be adapted in either direction, or both just to deter voter participation altogether.
It would be shocking, though, if it turned out that Russia was the only country trying to influence US elections, though, instead of the only one that has been publically exposed.
I think many countries assessed that they were capable of it, but many would think this was a casus belli. Had Clinton been elected instead, she probably would have sought additional sanctions and a firmer stance against Russia because of this.
Yet, with an exception of Iran, the countries with most aggressive foreign policies (Russia, China, North Korea, Saudi Arabia, and Turkey) seem to currently support the election of Republican nominees.
