"You don't want your national security adviser compromised with the Russians", Yates told a Senate panel investigating Russia's election interference.
Yates, who was testifying at a Senate Judiciary subcommittee hearing on Russian meddling in the 2016 presidential election, said she first warned the White House of the Department of Justice's concerns on January 26.
During her testimony, Ms Yates said she again met with Mr McGuan on 27 January to discuss his concerns.
Eighteen days after first learning of Yates's concerns, Trump fired Flynn, saying he no longer had confidence in having him as a key White House adviser.
Commenting on this conversation on Fox news, President Donald Trump blamed the Obama administration for not vetting Flynn.
Mr Flynn was sacked from the DIA in 2014 for what officials familiar with the issue said was a disruptive management style that included instructing analysts to find intelligence substantiating improbable theories that some subordinates came to call "Flynn facts".
The New Jersey governor said he told Trump about disagreements he had with Flynn. Mr Franken speculated that the only explanation he could think of was that there were other Trump administration officials that had contacts with the Russian government.
White House Press Secretary Sean Spicer was asked Monsday about Flynn's vetting by the Trump transition team, and he sidestepped the question, countering with his own question about why no steps had been taken by the Obama administration to change the status of Flynn's clearance from April. 2016 until the time it was suspended. Rice, a longtime target of Republicans, declined because her attorney said the invitation came late and without bipartisan consent. She did not shed much light on other aspects of investigations of allegations that Russian Federation meddled in the 2016 United States election and whether there was collusion between President Donald Trump's campaign and Moscow.
Chelsea keeps Tottenham 4 points behind in title pursuit
A draw isn't the worst result , but this is a match we should be winning. though titles aren't won on should, obviously. Mario Melchiot has hailed Antonio Conte's intense approach as the key to Chelsea's outstanding Premier League season.
"We weren't the only ones that knew all of this", said Yates.
The recent revelations came on the same day that former acting Attorney General Sally Yates testified about the events that led to Michael Flynn's firing from his position of National Security Advisor.
Mr Obama warned his successor less than 48 hours after the November election during a conversation in the Oval Office, former Obama officials said. She did absolutely the right thing from what I can tell. Press secretary Sean Spicer said yesterday, "Well, you don't vet on a security clearance, that's why you get a security clearance". Flynn served under Obama as defense intelligence chief before Obama dismissed him from that post.
Mr Trump has repeatedly said he has no ties to Moscow and is not aware of any involvement by his aides in any Russian interference in the election.
Mr Trump has dismissed FBI and congressional investigations into his campaign and Russian Federation as a "hoax".
"Director Clapper reiterated what everybody, including the fake media already knows - there is "no evidence" of collusion w/ Russian Federation and Trump", Mr Trump said.
Monday, CBS News also confirmed former President Obama counseled then-President-elect Trump to pick another national security adviser immediately after the election.
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