Thursday, November 10: President Obama hosts President-elect Trump for a 90-minute meeting at the White House. During the meeting, Obama personally raises his concerns about Michael Flynn’s job performance during his tenure leading the Defense Intelligence Agency. By then, it was assumed Trump would appoint Flynn, one of his top campaign aides and a former Army lieutenant general, to an administration post.

Thursday, November 17: Trump announces that Flynn will serve as his national-security adviser. The post does not require Senate confirmation.

Thursday, December 29: In retaliation for Russia’s election meddling, the Obama administration expels 35 Russian diplomats, seizes two of Moscow’s U.S. compounds, and sanctions top Russian government officials. According to filings from the special counsel’s office, which were publicly released in December 2017, Flynn calls an unnamed senior official on the Trump transition team at Mar-a-Lago to discuss what he should tell Russian Ambassador Sergey Kislyak about the administration’s stance on the sanctions. (Kislyak had contacted him the day before.) They and other members of the team at the president’s Florida estate agree that they do not want Russia to escalate the diplomatic crisis.

After the initial call, Flynn speaks with Kislyak multiple times by phone and urges him not to exacerbate the situation. U.S. intelligence officials intercept the calls as part of their routine surveillance of foreign dignitaries.

Friday, December 30: Russian President Vladimir Putin announces that his government will not impose its own sanctions as payback against the United States. Trump praises Putin’s move on Twitter shortly thereafter.

Great move on delay (by V. Putin) - I always knew he was very smart! — Donald J. Trump (@realDonaldTrump) December 30, 2016

Friday, January 6: The U.S. intelligence community releases a 26-page report concluding that Russian intelligence agencies used cyberattacks and stolen documents to undermine Hillary Clinton’s presidential bid and the American electoral process. Trump releases a bland statement asserting “there was absolutely no effect on the outcome of the election.”

Thursday, January 12: Citing an unnamed senior government official, Washington Post columnist David Ignatius is the first to report about Flynn’s December 29 calls with Kislyak.

Friday, January 13: Sean Spicer, the incoming White House press secretary, tells reporters that Flynn’s conversations with Kislyak centered on logistics for a post-inauguration call between Putin and Trump. “That was it,” he said, “plain and simple.”

Sunday, January 15: Trump transition officials defend Flynn on the Sunday- morning political talk shows. Vice President-elect Mike Pence tells CBS’s Face the Nation that the retired general “did not discuss anything having to do with the United States’ decision to expel diplomats or impose censure against Russia” in his talks with Kislyak. Reince Priebus, the incoming White House chief of staff, tells NBC’s Meet the Press that “the subject matter of sanctions or the actions taken by the Obama [administration] did not come up in the conversation.”