(CNN) 18 days.

That's how long it took the White House to fire national security adviser Michael Flynn after acting Attorney General Sally Yates met with White House counsel Don McGahn to inform him that Flynn wasn't telling the truth about his interactions with Russian ambassador Sergey Kislyak and, as a result, represented a blackmail risk.

"We believed that General Flynn was compromised with respect to the Russians," Yates said in a Senate subcommittee hearing aimed at gathering details of the Russian hacking of the 2016 election on Monday in Washington. She added: "Logic would tell you that you don't want the national security adviser to be in a position where the Russians have leverage over him."

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Yates noted that she met with McGahn on January 26 and again on January 27 to inform him of the fact that Flynn's assertions -- as relayed in the media by Vice President Mike Pence -- were simply not accurate. She did so both because she thought the Justice Department owed it to the vice president to tell him what they knew but also because they knew the Russians knew of Flynn's problems.

Yates added that McGahn asked for -- and was granted -- the chance to examine the materials that led the Justice Department to their conclusion. She said she did not know whether McGahn or anyone else in the White House actually reviewed those materials. Yates also repeatedly said she decided to inform McGahn and the White House of what they knew of Flynn so the White House could "take action."

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