(Andrew Harnik | The Associated Press) In this Oct. 31, 2017, file photo, Sen. Richard Blumenthal, D-Conn., speaks next to a poster depicting an online ad that attempted to suppress voters as Facebook's General Counsel Colin Stretch, Twitter's Acting General Counsel Sean Edgett, and Google's Law Enforcement and Information Security Director Richard Salgado testify before a Senate Committee on the Judiciary, Subcommittee on Crime and Terrorism hearing on Capitol Hill in Washington. The Feb. 16, 2018, election-interference indictment by U.S. special counsel Robert Mueller underscores how thoroughly U.S. social-media companies like Facebook and Twitter were played by Russian propagandists.