Monday, Yates confirmed she had two in-person meetings with White House counsel, Don McGahn in January, warning him that then-National Security Adviser Michael Flynn had misled Vice President Pence about his contacts with the Russian ambassador to the U.S.
Yates testified that she reached out to and met with White House Counsel Donald McGahn about Flynn, who was sacked in February for misleading Vice President Mike Pence about his conversations with the Russian ambassador to the United States.
Republicans asked a lot of questions about "unmasking" - the practice wherein intelligence officials request the identity of Americans subject to surveillance because they communicated with foreign subjects of USA intelligence spying.
Trump fired Flynn, a retired general, for failing to disclose discussions with Russian ambassador Sergey Kislyak about United States sanctions against Moscow and for not telling the truth about them to Vice President Pence.
Her testimony adds to Flynn's potential legal problems, outlining concerns at the highest level of the Justice Department that Flynn's conversations with the Russian diplomat during the transition may have violated the law.
"But also more importantly, for the discussion today about Russian Federation, [she was] really laying out that this was just not a heads-up she gave the White House".
"They must be congratulating themselves because this exceeded their wildest expectations", he said. "And I believe they will continue to do so".
White House Chief of Staff Reince Priebus and Press Secretary Mr Spicer both asserted that White House counsel investigated Ms Yates' information and found nothing.
Yates did not directly say whether Flynn had broken any laws, or whether he would or should face any criminal charges as a result. "The Russians also knew".
- During her appearance before a Senate Judiciary subcommittee, Sally Yates was asked about her refusal to enforce President Trump's initial travel order while she was acting Attorney General. "And we believed Gen. Flynn was compromised with regard to the Russians". However, Yates, who has been with the DOJ for several years, had quick answers for Cruz's questions, drawing praise from liberals.
After warning the White House, Yates was sacked on January 30 for refusing to comply with an executive order barring travel from seven predominantly Muslim countries on the grounds thatthe ban was unlawful.
During their conversation, Mr. Obama warned Mr. Trump not to hire Flynn, whom he himself fired in 2014 from his position as head of the Defense Intelligence Agency because of his temperamental issues.