Special Counsel Robert Mueller has charged former National Security Adviser Mike Flynn with “willfully and knowingly” making false statements to investigators looking into Russian interference in the 2016 election.

According to a court filing Friday at the federal district court in Washington, Flynn allegedly falsely told investigators that he did not ask Russian Ambassador Sergey Kislyak to “refrain from escalating the situation” in response to U.S. sanctions imposed against Russia Dec. 29, 2016. Flynn also said he did not remember the ambassador then telling him that Russia would indeed moderate its response, which Mueller's team alleges is false.

Flynn also lied, the special counsel alleges, about a conversation with Kislyak on Dec. 22. He allegedly said he had not asked Kislyak to delay a vote on, or defeat, a pending U.N. Security Council resolution and that the Russian ambassador never described to him the country's response to that request.