Flynn was charged on Thursday with one count of lying about his private discussions with Sergey Kislyak, the Russian ambassador, regarding US sanctions being imposed on Moscow by the government of then president Barack Obama, a court document showed.
"On or about January 24, 2017, defendant Michael T. Flynn did willfully and knowingly make materially false, fictitious, and fraudulent statements and representations" over a government matter, federal prosecutors said in the two-page charge sheet.
The fourth, and most senior, figure indicted so far in Special Counsel Robert Mueller's investigation into Russian interference in last year's election, Flynn was scheduled to appear in court later Friday morning for a plea hearing.
According to an unconfirmed report from NBC, he is planning to plead guilty.
The charges allege that Flynn falsely denied to investigators that, just as the Obama administration was announcing new sanctions and the expulsion of 35 Russian diplomats over Moscow's interference in the 2016 election, Flynn privately asked Kislyak to refrain from escalating the situation by retaliating.
Flynn also allegedly lied to investigators about Kislyak's subsequent answer that Russia would moderate its response, according to the charge document.
At the time Flynn was a campaign advisor with no official US government role, but it was known that he would likely become Trump's White House national security advisor -- a post he was forced to resign in February, just weeks after the president took office, due to concerns over his contacts with Russia.
Flynn, who once headed the Defense Intelligence Agency, is also accused of lying about secretly asking Kislyak in late December to delay a vote or defeat a pending UN Security Council resolution, according to the charges.
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