For a well documented case: http://www.stratcomcoe.org/internet-trolling-hybrid-warfare-...
So does JTRIG[1][2], and probably many other groups as well. Russia isn't the only suspect for this kind trolling.
Human rights violations in the U.S. are also well documented by China:
http://blogs.wsj.com/chinarealtime/2015/06/26/china-issues-r...
Likewise, Russia has a well documented history of sponsoring online propaganda campaigns, and most people who aren't delusional or paid shills would agree.
Two negative things about two different countries can in fact both be based in truth. Weird.
I very much doubt they're competent enough to pull something like this convincingly here in the US and avoid early detection and counter-intelligence response. Thus far no evidence whatsoever was presented that any of this was Russian, let alone state sponsored. That's either some truly elite level GRU work, to the standard we have not ever seen before, or there is, in fact, no "paid Russian trolls" on The_Donald. My opinion: there's no way in hell they could pull this off without getting noticed _well before_ the anointed Democratic candidate lost the election.
What?
gamergate, /pol, /b, alt-right, the_donald, antifa use online trolling. In context, saying a state actor uses online trolling is an extremely conservative claim. I'm sure there's online trolling in favor of and sponsored by US, Chinese and Macedonian interests (to name a few) too - but Russia's actions are much better documented.