But after almost two dramatic hours in a courtroom discussing his crimes, he asked to postpone his sentencing for several months so he can have more of an opportunity to cooperate in federal investigations and attempt to mitigate the judge's disgust with his actions.

"I want to be frank with you, this crime is very serious," federal Judge Emmet Sullivan said in the courtroom Tuesday. "Not only did you lie to the FBI, you lied to senior officials in the incoming administration."

Flynn, who pleaded guilty last year to lying to FBI agents in a January 24, 2017, interview in the West Wing of the White House, told the judge on Tuesday "I was aware" that lying to the FBI was a crime. He said he accepted responsibility for his actions.

Prosecutors from special counsel Robert Mueller's office had asked the judge to give Flynn little to no jail time because he had cooperated extensively with them and in at least one other investigation, a case in Virginia against Flynn's former business associates in which they are accused of illegally lobbying for Turkey. Prosecutors said Tuesday that Flynn had already given the "vast majority of cooperation" the judge should consider for his sentence but it was possible he could still help in other prosecutorial actions.

But Sullivan, of the US District Court for the District of Columbia, veered the sentencing hearing off its course.

After formally accepting Flynn's guilty plea, the judge threw a series of questions at him that highlighted how unusual Flynn's case is and how consequential his actions may be.

Did Flynn believe he was not guilty? Did he think he was entrapped by the FBI when they interviewed him without a defense attorney present? Had Mueller's team considered charging Flynn with other crimes, including treason?

Flynn and the lawyers' answers to all of these questions were no.

Yet Sullivan pressed on, his voice growing more shrill as he discussed Flynn's actions.

Flynn lied even "in the presence of the White House," Sullivan added. "You can't minimize that."

"I am not hiding my disgust, my disdain for your criminal offense," Sullivan said, pausing between each statement. "Yes, your honor," Flynn said. He was not asked a question.

At one point, Sullivan wrongly suggested Flynn had acted as an illegal agent of a foreign government while serving as national security adviser. "That undermines everything this flag over here stands for. Arguably, you sold your country out," Sullivan said. Later, the judge walked that comment back, acknowledging that Flynn's unregistered lobbying for the Turkish government ended in November 2016, while Flynn worked on the Trump campaign and transition and before they took the White House.

As much of the hearing unfolded and the tension in the room grew, there was little obvious reaction from members of the Flynn family, some of whom have embraced and amplified unfounded claims of FBI misconduct on their social media accounts. Many of them sat in the front row of the courtroom, and when the judge rhetorically asked if his "treason" implication was incorrect, some of Flynn's supporters loudly said, "Yes."

Before the hearing, about a dozen family members and friends present had appeared to be in a good mood, with Flynn even telling his supporters as he entered the courtroom, "You made it."

Trump himself had wished Flynn "good luck" in a Tuesday morning tweet, adding that it "will be interesting to see what he has to say."

Good luck today in court to General Michael Flynn. Will be interesting to see what he has to say, despite tremendous pressure being put on him, about Russian Collusion in our great and, obviously, highly successful political campaign. There was no Collusion! — Donald J. Trump (@realDonaldTrump) December 18, 2018

Following Sullivan's courtroom reprimands Tuesday, Flynn took a break to meet privately with his attorneys. When they returned to the courtroom, Flynn's legal team told the judge they'd like more time before his sentencing.

Both sides now have until March 13 to file a status report with the court. Flynn's sentencing date has not been rescheduled, and will likely not happen until there is a conclusion in the separate federal criminal case in Virginia, in which his lobbying partner has pleaded not guilty.

Flynn left the courthouse without speaking to reporters. Security guards ushered him to a waiting car as ralliers and protesters chanted "USA, USA."

Sullivan ordered Flynn to stay within 50 miles of Washington and to surrender his passport. The judge said he was imposing the restrictions because they were typical for defendants released on personal recognizance but he had just learned Flynn had not been under such a restriction. Sullivan said the restriction starts January 4 and he was approving already-planned international travel that the court had been informed about.

After the hearing, White House press secretary Sarah Sanders dug in on the entrapment accusation.

"The FBI broke standard protocol in the way that they came in and ambushed Gen. Flynn and in the way that they questioned him and in the way that they encouraged not to have White House counsel's office present," she said at the White House press briefing.

A key Mueller witness

Over the past year, Flynn has given Mueller a key witness on some of the most scrutinized moments during the Trump campaign, transition and first month in the White House -- while also turning the former Army lieutenant general into a political cause backed by conservatives wary of Mueller's approach. "Nothing has been held back" during the cooperation sessions, Flynn's defense lawyer told the court on Tuesday.

Flynn pleaded guilty last December to one count of lying to the FBI. In his January 2017 interview with two FBI agents, he downplayed the substance of his interactions with then-Russian Ambassador Sergey Kislyak during the 2016 presidential transition. Flynn had in fact asked Kislyak for certain policy responses from Russia following US sanctions and before a United Nations Security Council resolution vote. Flynn also lied about his lobbying work for Turkey throughout 2016.

He barely spoke to the judge in the courtroom Tuesday, other than answering questions with two- or three-word statements.

Because his guilty plea had been accepted by a different federal judge, who then appears to have recused himself from the case, Sullivan reviewed Flynn's crimes on Tuesday and made sure Flynn still wanted to admit his guilt.

"I would like to proceed, your honor," Flynn said about his guilty plea. "Because you're guilty of this offense?" Sullivan asked. "Yes, your honor," Flynn said, nodding.

Three previous defendants in Mueller's probe -- Trump's former personal attorney Michael Cohen, the Dutch lawyer Alex van der Zwaan and former Trump campaign adviser George Papadopoulos -- pleaded guilty to the same crime of lying. Each received sentences that included prison time, with Cohen getting two months (Cohen was also sentenced to three years in a separate case). But none of those men helped investigators as broadly, willingly or sincerely as Flynn, Mueller's team has said.

Sullivan, however, drew the contrast that Flynn was singular among them because of his position in the military and the administration.

"My guess was not one of those defendants was a high-ranking government official who while employed by the President of the United States ... made false statements on the premises of and in the West Wing of the White House," Sullivan said.

Another defendant, former Trump campaign deputy Rick Gates, also pleaded guilty to a lying charge in Mueller's probe. He continues to cooperate with the investigation and has no set sentencing date.

The FBI's approach

Flynn's sentencing has been shaded over the past three weeks by criticism of the FBI's actions when it first approached him in the White House on January 24, 2017.

Flynn's defense team first raised the issue in a memo to Sullivan last week. The defense lawyers argued that Flynn should be spared jail time because he had lied under different circumstances than van der Zwaan and Papadopoulos, who had been warned they could be prosecuted for lying to the FBI.

Flynn spoke to the FBI agents with no lawyer present and hadn't been warned of the potential legal consequences. He also did not involve the White House counsel's office, and the FBI did not involve the Justice Department in his interview.

Flynn was so relaxed, investigators said, that they did not have the impression that he was lying during the interview, according to memos from the agents. Even so, the FBI knew that when Flynn said he hadn't asked for certain responses from Kislyak to the American sanctions against Russia or a United Nations Security Council resolution, he was lying.

Tuesday, Sullivan asked Flynn's attorneys if the former national security adviser was "entrapped by the FBI." His defense lawyer said, "No, your honor."

Another FBI memo about the January 24, 2017, interview, released Monday night, further solidified that Flynn wrongly denied he had tried to influence the Russian government's reaction to sanctions and intentions at the UN.

Flynn first met Kislyak in 2013 while director of the Defense Intelligence Agency, and he had developed the relationship with the Russian government since then. Court documents made public last year show that members of Trump's transition team knew about Flynn's requests to the ambassador a month before the inauguration.

Flynn is also central to the potential obstruction of justice case surrounding Trump's interactions with former FBI Director James Comey. According to a memo Comey wrote in February 2017, the President asked him to drop the investigation into Flynn.

Mueller's team has described on multiple occasions how Flynn misled members of the Trump administration about his contacts with Kislyak, which then prompted those public officials to share false information with the American public.

'Could he have been charged with treason?'

Sullivan stunned the courtroom when he asked if Flynn conduct "rises to the level of treasonous activity."

Prosecutor Brandon Van Grack, speaking for the special counsel's office, said prosecutors did not consider charging Flynn with treason.

Sullivan asked again: "Could he have been charged with treason?"

Later, the judge walked back his treason questions. "I'm not suggesting" Flynn committed treason, he said.

"I was just trying to determine the benefit and the generosity of the government," he said. "Don't read too much into the questions I ask."

But then, as an aside, Sullivan commented how much he disagreed with the no-jail-time sentence of former Gen. David Petraeus , who shared classified information with his biographer and lover. Petraeus pleaded guilty to a misdemeanor offense in 2015 and served two years on probation. He also was ordered to pay a $100,000 fine.

Sullivan's closing words to the courtroom were: "Happy holidays."

Turkey project

Aside from Flynn's conversations with the Russian, he admitted to lying about his lobbying work for the Turkish government as it sought to build American support for the extradition of a cleric and political opponent living in Pennsylvania.

Flynn's two former business associates were indicted by the Justice Department on Monday for working on this project, which included Flynn authoring an op-ed in a Washington newspaper that sympathized with the current Turkish government and demonized the cleric. The op-ed published on Election Day 2016. The former business associates also accepted payments for the work through Flynn's company, the Flynn Intel Group, according to the charging document.

One of the men, Flynn Intel Group co-founder Bijan Rafiekian, also known as Bijan Kian, appeared in a Virginia courtroom Tuesday and pleaded not guilty to charges of conspiracy and illegally acting as a foreign agent in the US.

The other defendant in the case, a Dutch-Turkish businessman, is charged with the same two crimes plus lying to the FBI. The businessman, Kamil Ekim Alptekin, lives in Istanbul and has not appeared in US court.

This story has been updated.