Late Monday, Facebook pushed back against rumors that its platform was exploited by Russian operatives trying to influence last year's Brexit vote. The company told BuzzFeed News in a delicate statement that it had not seen "significant coordination" between Russia-linked accounts, whether with "ad buys or political misinformation targeting Brexit voters." The denial came just hours before British Prime Minister Theresa May accused Russia of meddling in elections and "planting fake stories."

Damian Collins, the head of the U.K. House of Commons' digital media and culture committee, has written to Facebook, Twitter, and Google asking for information in regards to Russian-linked accounts that may have spread misinformation or propaganda about Brexit. Facebook CEO Mark Zuckerberg has yet to respond to Collins' inquiry, and the company offered only Monday's statement.

Days after the 2016 U.S. presidential election, Zuckerberg said the idea that fake news on Facebook affected the election was "pretty crazy," adding that it was not empathetic to assume "that the only reason someone could have voted the way they did is because they saw fake news." Zuckerberg has since had to walk back that statement, after it came out last month that 126 million users — about 40 percent of the U.S. population — were exposed to fake news on Facebook during the 2016 election.

Additionally, Twitter has faced its own Russia allegations: Last Friday, Wired published "a small snapshot" of cached Twitter posts from 29 different Russian-linked accounts in 2016 that spread provocative pro- and anti-Brexit propaganda to more than 260,000 people. Kelly O'Meara Morales