Former deputy attorney general Sally Q. Yates told Congress on Wednesday that President Trump’s incoming national security adviser Michael Flynn in late 2016 had secretly “neutered” Obama administration actions toward Russia, prompting an investigation that consumed the early days of Trump’s presidency.

Yates has been a target of Trump and many Republicans for her brief oversight of the investigation of Russia’s election interference and possible collusion with the Trump campaign four years ago. She testified via video before the Senate Judiciary Committee, whose chairman, Sen. Lindsey O. Graham (R-S.C.), has been highly critical of the FBI’s handling of that case.

Trump attacked Yates before the hearing began, tweeting that she “has zero credibility” and declaring her “part of the greatest political crime of the Century, and ObamaBiden knew EVERYTHING!”

Graham’s review of the Russia investigation is one of two in the Republican-controlled Senate focused on reviewing the FBI’s investigation of the Trump campaign. The president’s allies leading those reviews say they are focused on exposing misconduct and working to restore public confidence in federal law enforcement. Critics, including congressional Democrats, say they are a politically motivated attempt to rewrite history and help the incumbent in an election year.

Seeking to use Yates to discredit the FBI’s investigations regarding the 2016 Trump campaign, Republicans instead got a spirited defense of that work as ethical and necessary, even though she was critical of some of the FBI’s moves at the time.

Graham pressed Yates in depth about a White House meeting on Jan. 5, 2017, in which President Barack Obama, Vice President Joe Biden and Obama national security adviser Susan E. Rice met with her and FBI Director James B. Comey to talk about Flynn’s recent phone conversations with Sergey Kislyak, Russia’s ambassador to the United States at that time.

The Obama administration had just expelled dozens of suspected Russian intelligence agents in response to the election interference. Obama and his aides expected Russia to retaliate, but it did not. FBI agents quickly learned the reason: Phone call intercepts showed Flynn had asked Kislyak not to.

“General Flynn had essentially neutered the U.S. government’s message of deterrence,” Yates said. Instead of rebuking the Russian government, she said, Flynn had been “conciliatory.”

Conservatives have rallied to defend Flynn and focused on the Oval Office meeting as evidence that the investigation of him was politically motivated. Yates denied that.

“That meeting was not about an investigation at all,” she said. “That is something that would have crossed the line.” If Obama or Biden, who is now the Democrats’ presumptive nominee to challenge Trump in November, had talked about the investigation of Flynn, “that would have set off alarms for me,” she said. The main point of the meeting, she said, was to figure out what the Russians were up to.

Days after Trump was sworn in as president, FBI agents went to the White House to interview Flynn about his conversations with Kislyak. In that interview, Flynn denied having discussed key elements of Obama’s new sanctions on Russia. Flynn ultimately pleaded guilty to having lied in that interview but later reversed course and fought the case. Earlier this year, the Justice Department asked for the case against Flynn to be dismissed, an issue still being weighed by the courts.

Republicans also questioned Yates’s approval of Foreign Intelligence Surveillance Court applications for former Trump adviser Carter Page. A lengthy report by Justice Department Inspector General Michael Horowitz found 17 significant errors or omissions in the court papers filed for surveillance in that case.

Yates said that if she had known about those errors at the time, she would not have signed those applications to the surveillance court.

“I wouldn’t sign anything that I knew to contain errors or omissions,” she said. “I would never knowingly do that.”

Yates said her main concern with the Page surveillance was that, in hindsight, it appeared the FBI agents substituted their own judgment for that of Justice Department prosecutors in deciding what pieces of information were important and worth telling the court.

Asked on July 13 if he plans to pardon former national security adviser Michael Flynn, President Trump said, "I think he was persecuted." (The Washington Post)

Trump reacted to Yates’s regret about the Page surveillance by tweeting that it was the “Political Crime of the Century” and, as he often does when discussing the FBI investigation of his campaign, called it “Treason!”

Yates denied a suggestion by Sen. John Neely Kennedy (R-La.) that senior federal law enforcement officials despised Trump and sought to prevent him from becoming president.

“No, Senator, they did not hate Trump,” Yates said. “I have to speak up here for the career men and women of the Department of Justice.”

Kennedy fired back that Yates and her colleagues “have tarnished the reputation of the FBI.”

After Yates spent several hours denying Republican accusations of corruption, political bias and dishonesty at the Justice Department, the committee chairman vowed to dig further into the issue of the Page surveillance, which was based in large part on a dossier of allegations against the Trump campaign compiled by a former British intelligence officer.

“I don’t buy for a minute that . . . only two people in the FBI knew the dossier was garbage and they didn’t tell anybody,” Graham said, adding he is determined “to make sure that the biggest system failure maybe ever at the FBI is not repeated.”