Wall Street Journal Reporter John McKinnon: Any other country could follow suit of Russia

Sen. Dianne Feinstein, D-Calif., speaks 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 during a Senate Committee on the Judiciary, Subcommittee on Crime and Terrorism hearing on Capitol Hill in Washington, Tuesday, Oct. 31, 2017, on more signs from tech companies of Russian election activity. (AP Photo/Andrew Harnik)

Just ahead of the Congressional hearing involving testimonies from tech companies like Google, Facebook and Twitter, Wall Street Journal Reporter John McKinnon describes how Russian operatives took control of their pages and ads to influence the 2016 presidential election.