'I warned White House about Michael Flynn'

Spicer described her visit to the White House to warn of Flynn as a "heads-up". Spicer said that if Obama "was seriously concerned" about Flynn's connections to Russian Federation or other foreign countries, he should have withheld Flynn's security clearance. Flynn served under Obama as defense intelligence chief before Obama dismissed him.

Trump, who fired Yates soon after taking office, fired off a series of pre-emptive strikes ahead of her appearance on Capitol Hill, accusing Obama of enabling Flynn and assailing Yates for allegedly leaking classified information.

The discussion between President Obama and President-elect Trump was revealed on Monday by NBC, citing three Obama administration officials.

Flynn, a former confidant of President Donald Trump, was sacked 18 days after taking office for failing to disclose that he discussed sanctions with Russia's ambassador in Washington while Barack Obama was still president.

According to a senior Obama administration source, "Flynn's name kept popping up".

Flynn had previously held a position in the former administration, but was sacked from his position as head of the defense intelligence agency.

"I think they may very well have seen Sally Yates' warning as just a political attack and not seen the fact that she was there with a very serious national security concern", Whitehouse told CNN.

Trump fired Flynn, a retired general, in February for failing to disclose talks with Ambassador Sergei Kislyak about United States. sanctions on Moscow and then misleading Vice President Mike Pence about the conversations.

The officials requested anonymity in order to disclose the private conversation.

But here are four reasons why the entire Russian Federation story - as it relates to the 2016 election, to former Trump National Security Adviser Michael Flynn, and to any allegations of collusion - isn't fake news.

Trump fired FBI Director James Comey on Tuesday, saying he had lost confidence in Comey over his handling of an election-year email scandal involving then-Democratic presidential nominee Hillary Clinton.

Yates was testifying before a Senate committee Monday about Russian interference in the 2016 election.

Trump tweeted Monday that Flynn was "given the highest security clearance by the Obama Administration - but the Fake News seldom likes talking about that".

The Associated Press reported last week that one sign taken as a warning by Obama officials about Flynn's contacts with Kislyak was a request by a member of Trump's own transition team made to national security officials in the Obama White House for the classified Central Intelligence Agency profile of Kislyak.

Yates testified at a Senate Judiciary subcommittee hearing that focused primarily on Flynn, and did not shed much light on other aspects of investigations of allegations that Russian Federation meddled in the 2016 US election and whether there was collusion between President Donald Trump's campaign and Moscow.

The second warning came in January, from the acting Attorney General Sally Yates. And Yates implied that Flynn misled the Federal Bureau of Investigation during a January 24 interview about his conversations with Kislyak.

Graham, along with Senators Ted Cruz (R-TX) and Charles Grassley (R-IA), and others, grilled Clapper and Yates over the unmasking of Flynn and his conversations with Russian ambassador Sergey Kislyak, and the subsequent leak to the Washington Post. But though she relayed her concerns to the White House counsel, there apparently was little sense of urgency.

She was joined in the meeting by a senior career official in the Justice Department.

The person was not authorized to discuss the testimony on the record.