President Trump’s former national security adviser, General Michael Flynn, pleaded guilty Friday to a single felony count of lying to the FBI about conversations he had last December with Russia’s ambassador to the U.S. Flynn’s plea came as part of a deal that will see him cooperate with special counsel Robert Mueller’s probe into alleged Russian meddling in the 2016 election, and could see Flynn testify against President Trump and members of his inner circle. The deal also raises the prospect that Flynn may have worn a wire for the FBI or otherwise secretly recorded conversations with administration officials. Documents handed to investigators as part of the plea deal show Flynn was ordered to speak with Russian Ambassador Sergey Kislyak by a “very senior” member of the presidential transition team—cited by many news outlets as  Jared Kushner, President Trump’s senior adviser and son-in-law. Kushner reportedly ordered Flynn to work with Russian officials to delay a U.N. Security Council vote on a resolution condemning illegal Israeli settlements in the occupied West Bank. On Saturday, President Trump reacted to the news as he prepared to leave the White House for fundraisers in New York.

President Donald Trump: “What has been shown is no collusion. No collusion. There’s been absolutely—there’s been absolutely no collusion. So, we’re very happy. And frankly, last night was one of the big nights.”

Over the weekend, Trump lashed out against the Russia investigation in a series of tweets, writing that the FBI’s reputation is “in tatters,” and repeating his claim that former FBI Director James Comey lied when he testified that Trump asked him to call off the bureau’s investigation into Michael Flynn. In another tweet, Trump wrote, “I had to fire General Flynn because he lied to the Vice President and the FBI.” Legal scholars say the tweet could be used to prove that President Trump committed obstruction of justice when he fired Comey as FBI director. On Saturday, Trump’s personal lawyer, John Dowd, claimed he was the one who drafted the tweet, saying he had made a mistake.