Former Acting Attorney General Sally Yates testifies about potential Russian interference in the presidential election before the Senate Judiciary Committee on Capitol Hill, Washington, DC, US May 8, 2017. [Photo/Agencies]

During a congressional hearing here, Yates told US lawmakers the fact that Flynn misled Vice President Mike Pence about his telephone conversation with the Russian Ambassador to the United States could have created a "compromise situation."

"We weren't the only ones that knew all of this," said Yates. "This was a problem because not only do we believe that the Russians knew this, but that they likely had proof of this information, and that created a compromise situation, where the national security advisor essentially could be blackmailed by the Russians."

"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," she added.

Flynn resigned on Feb. 13 after it was revealed that he had misled Vice President Mike Pence about his telephone conversation with the Russian Ambassador to the United States, in which he made comments about US sanction against Russia.