Top executives from Facebook Inc. and Twitter Inc. defended their companies in the U.S. Congress on Wednesday over what lawmakers see as a failure to combat continuing foreign efforts to influence U.S. politics.

Facebook Chief Operating Officer Sheryl Sandberg, who testified alongside Twitter Chief Executive Jack Dorsey, acknowledged to the Senate Intelligence Committee that the company was too slow to respond to Russian efforts to interfere in the 2016 U.S. election and general American political discourse, but insisted it is doing better.

"We've removed hundreds of pages and accounts involved in coordinated inauthentic behavior — meaning they misled others about who they were and what they were doing," Sandberg said.