"Does Google now know the full extent to which its online platforms were exploited by Russian actors in the election two years ago?" Rep. Jerry Nadler, a Democrat from New York and ranking member of the House Judiciary Committee, asked the search engine's chief executive during Tuesday's hearing.

?"We have - we undertook a very thorough investigation, and, in 2016, we now know that there were two main ad accounts linked to Russia which advertised on Google for about $4,700 in advertising," Pichai responded.

"A total of $4,700?" Nadler asked to confirm.

"That's right," the Google executive replied.