Flynn was interviewed by the FBI about his telephone conversations with Russia's ambassador to the U.S., a sign his ties to Russia had caught the attention of law enforcement officials. But in the White House's retelling of Flynn's stunning downfall, his error was not that he discussed U.S. sanctions with the Russian before the inauguration — a potential violation of a rarely enforced law — but the fact that he denied it for weeks, apparently misleading Vice President Mike Pence and other senior Trump aides about the nature of the conversations. White House officials said they conducted a review of Flynn's interactions, including transcripts of calls secretly recorded by U.S. intelligence officials but found nothing illegal.
Pence, who had vouched for Flynn in a televised interview, is said to have been angry.
"The evolving and eroding level of trust as a result of this situation and a series of other questionable incidents is what led the president to ask General Flynn for his resignation," White House spokesman Sean Spicer said Tuesday.
Flynn, in an interview with The Daily Caller News Foundation, said Monday "there were no lines crossed" in his conversations with Russian Ambassador Sergey Kislyak.
The explanation of the episode left many questions unanswered, including why Trump didn't alert Pence to the matter and why Trump allowed Flynn to keep accessing classified information and taking part in the president's discussions with world leaders up until the day he was fired.
White House officials struggled to explain why Trump counselor Kellyanne Conway had declared the president retained "full confidence" in Flynn just hours before the adviser had to submit his resignation.
Trump initially thought Flynn could survive the controversy, according to a person with direct knowledge of the president's views, but a pair of explosive stories in The Washington Post in recent days made the situation untenable. As early as last week, he and aides began making contingency plans for Flynn's dismissal, a senior administration official said. While the president was said to be upset with Flynn, he also was angry with other aides for "losing control" of the story and making his administration look bad.
Pence spokesman Marc Lotter said Pence became aware that he had received "incomplete information" from Flynn only after the first Washington Post report Thursday night. Pence learned about the Justice Department warnings to the White House around the same time. The officials and others requested anonymity.
On Jan. 26, Acting Attorney General Sally Yates contacted White House counsel Don McGahn to raise concerns about discrepancies between the public accounting and what intelligence officials knew to be true about the contacts based on routine recordings of communications with foreign officials in the U.S.
The Justice Department warned the White House that the inconsistencies would leave the president's top national security aide vulnerable to blackmail from Russia, according to a person with knowledge of the discussion. The president was informed of the warnings the same day, Spicer said. Flynn was interviewed by the FBI around the same time, according to a U.S. official was briefed on the investigation.