https://www.theverge.com/2017/9/6/16263704/russia-election-hacking-facebook-ad-spending

A Russian company that created fake accounts and pages purchased $100,000 worth of advertising during the US election last year, the company said. The Washington Post reported that Facebook traced the fake accounts to a Russian “troll farm” that has a history of promoting Russian propaganda. The ads began running in the summer of 2015, Facebook said, and a small number of them mentioned candidates Donald Trump and Hillary Clinton.

Other ads promoted posts focused on polarizing issues, such as racial tensions or LGBT rights. The tactic, which Russians have also employed on Twitter, is designed to create internal divisions within the United States and erode trust in the democracy. “The vast majority of ads run by these accounts didn’t specifically reference the US presidential election, voting or a particular candidate,” Facebook’s chief security officer, Alex Stamos, said in a blog post.