President Trump’s first national security adviser, Michael Flynn, was involved in “a compromise situation” where he “essentially could be blackmailed by the Russians,” former acting Attorney General Sally Yates testified before a Senate subcommittee hearing Monday.

Yates testified that she warned the White House in January that Flynn had misrepresented his contacts with Russian Ambassador Sergey Kislyak during the transition, confirming accounts that have been circulating in the press for the past few months.

Flynn told Vice President Mike Pence and others that he and Kislyak did not discuss the topic of President Obama’s sanctions on Russia, which were issued in response to Russian email hacks of prominent Democrats. But in fact, surveillance of Kislyak revealed that Flynn did in fact discuss sanctions with the ambassador, according to reports.

At the hearing, Yates didn’t get into specifics about what the intelligence showed about Flynn, but she described her two meetings with White House counsel Don McGahn on the topic — on January 26 and 27 — in general terms.

Yates said she wanted to brief the White House about Flynn for a few reasons. First, she said, “the underlying conduct that General Flynn had engaged in was problematic in and of itself.” Second, she thought Pence should know that the information he was given wasn’t accurate. Third, she said she was concerned that the American people had been misled.

But fourth, she said, “the Russians also knew that General Flynn had misled the vice president and others,” and “this was a problem,” because they likely “had proof of this situation,” and this potentially exposed Flynn to blackmail.

“To state the obvious, you don’t want your national security adviser compromised with the Russians,” Yates said.

After the first meeting, Yates said she was asked to return to the White House by McGahn for some follow-up questions the next day.

She said there were four topics on the agenda. First, she testified, McGahn asked “essentially, why does it matter to DOJ whether one White House official lies to another?” She said McGahn followed up by asking about Flynn’s potential criminal exposure, whether taking action against Flynn could impede any investigation against him, and whether the White House could examine the underlying evidence in this matter.

Yates says she didn’t know whether the White House did end up looking at the underlying evidence — because January 30 was her last day at the Justice Department. Trump fired her that day because she had refused to defend his immigration and travel order in court.

Why did Trump take so long to fire Flynn?

Yates’s public testimony once again raises the question of why Trump waited so long to fire Flynn.

Yates briefed McGahn on January 26 that Flynn could be “blackmailed” and “compromised” by the Russians. But that doesn’t seem to have spurred the White House to act. For two and a half weeks after that revelation, Flynn remained in his post as the top White House aide working on foreign policy and national security.

On February 13, however, an account of Yates’s meetings with McGahn leaked to the Washington Post’s Adam Entous, Ellen Nakashima, and Phil Rucker. Later that night — once the news was public and the administration was embarrassed — Trump finally fired Flynn.

Trump’s judgment in hiring Flynn in the first place was already in question. Monday morning, NBC News reported that President Obama warned Trump against naming Flynn national security adviser during the transition — though this seems to have been based on general concerns about Flynn’s temperament rather than any connections to Russia. (Obama fired Flynn from his job heading the Defense Intelligence Agency, reportedly due to management issues.)

Still, the idea that the White House would be briefed that a national security adviser was “compromised” by Russia and yet decide to keep him in his post for the foreseeable future remains astonishing.

And one of the biggest unanswered questions here is still whether Flynn was freelancing when he spoke to Kislyak about sanctions during the transition, or whether he was doing so at President-elect Trump’s request. The hearing, however, did not shed any light on that.