https://www.recode.net/2017/9/20/16340410/facebook-google-political-ads-russia-fec-letter-democrats

A group of House and Senate Democrats are calling on the U.S. government to issue new “guidance” to stop foreign advertisers from spending money on Facebook, Google and other web platforms in a bid to influence American elections.

Federal law already bars that sort of political spending, but lawmakers — including Rep. John Sarbanes and Sen. Elizabeth Warren — stress in a letter to the Federal Elections Commission that countries like Russia “have routinely deployed sophisticated tactics in making political expenditures to evade detection.”