Yates briefly led the U.S. Justice Department until Trump fired her on January 30 for declining to defend his travel ban on seven Muslim-majority countries.
That same day, White House press secretary Sean Spicer asserted that Trump had given Flynn due process in the interval between Yates' warning and the national security adviser's ultimate firing.
Notably, Trump's own White House requested the House and Senate investigations after he took to Twitter on a Saturday morning and accused Obama of tapping the phones in Trump Tower.
In December, before Trump assumed office, Flynn talked to Russian Ambassador Sergey Kislyak about potentially lifting US sanctions President Barack Obama had just levied on Russia.
Yates and Clapper both denied leaking classified information to the press. Just because someone comes in and gives you a heads-up about something and says I want to share some information doesn't mean you immediately jump the gun and go take an action. She also said that her office informed the White House of this 18 days before Flynn was sacked.
Flynn's own contacts with Russia have also raised eyebrows, including an appearance at a 2015 gala for state-sponsored Russian news network RT, during which he was photographed seated next to Russian President Vladimir Putin.
Nearly two hours after Trump's tweet, Merriam-Webster's official Twitter account posted that although they were reluctant, they had to establish the difference between "council" and "counsel". If Flynn was such a threat to national security, then why was his clearance reauthorized by Team Obama? Flynn was sacked as head of military intelligence by the Obama administration in 2014 amid questions about his management style and reports of insubordination.
In addition to his tweet about Flynn's security clearance, Trump also suggested on Twitter that Yates had tipped off journalists about Flynn's conversations with the Russian ambassador.
During that section of the hearing, Clapper described as accurate a report in the Guardian newspaper that British intelligence officials became aware in late 2015 about suspicious interactions between Trump advisers and Russian agents, and that the information was passed on to USA intelligence agencies.
The hearing was led by South Carolina's Republican Senator Lindsey Graham. "And the Russians use compromise material information in a variety of ways, sometimes overtly, sometimes subtly", she said.
Oklahoma Senate OKs $510 million in tax revenue
All you want to do is tread water. "Do you want to have sufficient officers in our correctional facilities?" the governor said. But the Oklahoma Tax Commission estimates the increase would raise just $20 million in additional revenue next year.
She said she told Mr McGahn she had seen statements regarding Mr Flynn's contacts with the Russian envoy "that we knew not to be truth".
Flynn's discussions with the Russian envoy have been scrutinized as part of an FBI and multiple congressional investigations into possible ties between Trump's campaign and Russia's meddling in last year's election.
Trump ignored Obama's advice and tapped Flynn for the top White House national security role.
And it is of a piece with the person-to-person message President Obama delivered Trump about Flynn in the two's November 10 sit-down - an extraordinary note of caution on a personnel matter for an incumbent President to aim at his successor.
Commenting on this conversation on Fox news, President Donald Trump blamed the Obama administration for not vetting Flynn.
But just hours before the hearing was to open, Trump's early support for Flynn was challenged by reports that then-president Barack Obama had strongly advised against giving him such a senior White House job.
The Mother Jones response will summarize where Trump's opponents stand: "The conclusion from Yates' testimony was clear: Trump didn't dump Flynn until the Kislyak matter became a public scandal and embarrassment". Flynn served under Obama as defense intelligence chief before Obama dismissed him.
Trump has repeatedly branded the issue "fake news" despite Clapper and other USA intelligence community leaders having concluded that Russian President Vladimir Putin himself was behind the interference operation.
Mr Trump has dismissed FBI and congressional investigations into his campaign and Russian Federation as a "hoax".