This probably explains Trump's morning chirping which in particular tried to attribute to the Obama administration the hiring of Flynn in his administration.
Yates, in her role as acting attorney general, warned White House counsel Don McGahn on January 26 that Flynn was lying when he denied - both publicly and privately - that he discussed USA sanctions on Russian Federation with Kislyak.
Though Yates would not discuss classified details of the Flynn matter, other people familiar with the matter said the issue she raised to McGahn were conversations between Flynn and Russian ambassador Sergey Kislyak, in which the two discussed easing USA sanctions against Russia.
Speaking before a Senate panel, Yates said it was Pence's public statements unknowingly misrepresenting Flynn's contacts with Russian Federation that led her in part to warn the White House.
How the White House could have failed to heed Yates's damning warnings about Flynn is particularly puzzling, but I suppose this is as good a theory as any.
At several points during her Senate testimony, Yates said she could not talk about details of the government's investigation into Russian Federation or Flynn's conduct since she was not allowed to discuss information that was classified or subject to investigation. And just four days after she issued the warning about Flynn, she directed the Justice Department not to enforce Trump's controversial travel ban.
"Gen. Clapper, is that accurate?" asked Feinstein.
Her account came on a dramatic day where Russian meddling in US politics returned to centre stage with a public hearing, the president tweeting about it, and the revelation Barack Obama warned Trump in their first meeting not to hire Michael Flynn.
The February resignation followed media reports that Mr Flynn had discussed US-imposed sanctions on Russian Federation with Ambassador Sergey Kislyak during the presidential transition period, which was contrary to the public representations of the White House.More news: SNP win the Scottish council elections
Word that President Obama directly warned Mr Trump suggests that concern over Mr Flynn's possible appointment spread to the highest level of government months before his departure.
Mr Flynn's forced February resignation followed media reports that he had discussed US-imposed sanctions on Russian Federation with Ambassador Kislyak, which was contrary to the public representations of the Trump White House.
Obama had cautioned against Flynn, whom he fired in 2014 as head of the defense intelligence agency, due to his poor record in administration and personnel management. From July 24, 2012, to August 7, 2014, Flynn held the title of highest-ranking military intelligence officer in the U.S. "That created a compromise situation, a situation where the national security adviser essentially could be blackmailed by the Russians".
"Well, unclassified is not - is not leaking", Clapper said, to laughter from many in the chamber.
Yates' appearance itself had been fraught with drama ever since House intelligence chairman Devin Nunes' delayed her House hearing at the last minute, as part of a chaotic three-week stretch that saw the House Russia investigation nearly fall apart and Nunes become the subject of a House ethics probe.
The Senate and House intelligence committees are continuing to investigate Russian interference in the 2016 election, including potential coordination between Russian officials and the Trump campaign or people close to the campaign. The revelation came after interviews with a host of former USA officials, most of whom spoke on the condition of anonymity in order to discuss sensitive national security information.
Marshall Billingslea, a former Pentagon and North Atlantic Treaty Organisation official, wanted the information for Flynn, his boss.
The panel is one of several looking into the scope and scale of ties between Trump's associates and Russian officials.