Facebook has found itself embroiled in another major controversy this month after the company revealed it sold ads to a shady Russian political company during the 2016 election. The controversy heated up again this week when lawmakers and a watchdog group called on Facebook to reveal everything it knows about the connection.

The social media giant revealed that more than 3,000 ads were purchased by Russian actors, but has refused to release the content of the ads due to “ongoing” investigations. As a result of Facebook’s secretiveness, the Campaign Legal Center is preparing to send a letter to Mark Zuckerberg this week that accuses Facebook of being “used as an accomplice in a foreign government’s effort to undermine democratic self-governance in the United States.” In another blow to Facebook, prominent U.S. lawmakers have harshly criticized the company for not telling the full truth.

“This is the Wild Wild West. I’m disappointed that Facebook didn’t come forward with this information about the Russians pushing people to anti-immigration rallies,” Sen. Mark Warner said. “They didn’t think that was relevant. But this was the tip of the iceberg. I think there’s going to be much more.”

Facebook likes to tout itself as an open platform, but when it refuses to be fully honest about its own dealings, it severely undermines its own philosophy.