• by Wendy Davis  @wendyndavis, November 10, 2017

Facebook should notify users who were exposed to Russian propaganda during the last election, Sen. Richard Blumenthal (D-Connecticut) says.

"You owe your users full information regarding when, where, and how they may have been unwitting participants in Russia's campaign to sow division and spread disinformation in the United States," Blumenthal wrote Thursday in a letter to Facebook CEO Mark Zuckerberg. "Facebook users deserve a comprehensive view of exactly what content they saw so they can understand and evaluate what they may see in the future."

The letter comes one week after Facebook told lawmakers that material created by Russian agents, including at least 3,000 ads, may have reached 146 million users -- 126 million on Facebook and an additional 20 million on Instagram.

Some of the ads that ran before the election obviously favored President Donald Trump. One called Hillary Clinton "a Satan," while another suggested that policies of Clinton and former President Barack Obama were responsible for "rapists, drug dealers, human traffickers, and others" illegally crossing the border.

"Consumer service entities like yours have long understood their duty to inform their users after mistakes are uncovered," Blumenthal wrote. "You too have an obligation to explain to your users exactly how Russian agents sought to manipulate our elections through your platform."

Blumenthal requested a response from Facebook by November 22.

A company spokesperson said Facebook has received the letter. The spokesperson also pointed to general counsel Colin Stretch's testimony last week to lawmakers. "The question of reaching out to individuals who may have seen it is a much more difficult and complex one, but we believe our commitment to transparency on this issue generally should address that," Stretch said.