The USA has, "by far," the world's largest cyber-army, and, years ago, clumsily made public that the USA government was developing "tools" and had full plans and intentions to hire people to use fake puppet accounts to "manipulate social media," to shill the USA government's viewpoints, and to discredit its opponents.
https://www.theguardian.com/commentisfree/cifamerica/2011/mar/17/us-internet-morals-clumsy-spammer
https://www.theguardian.com/technology/2011/mar/17/us-spy-operation-social-networks
http://www.reuters.com/article/us-election-intelligence-commentary-idUSKCN10F1H5