WASHINGTON — Former national security adviser Michael Flynn pleaded guilty Friday to lying to the FBI, the first guilty plea by a senior aide to President Donald Trump arising from an investigation into possible ties between the Russians and Trump’s 2016 campaign. According to a two-page charging document filed by special counsel Robert Mueller, Flynn “willfully and knowingly” lied to the FBI in January about two December phone calls he had with then Russian Ambassador Sergey Kislyak. Flynn told the FBI he did not discuss U.S. sanctions against Russia or a U.N. resolution on Israeli settlements with Kislyak – a claim refuted by U.S. intelligence officials who intercepted the calls. Flynn didn’t speak in court Friday, but in a statement the retired general cited his years of military service before acknowledging “that the actions I acknowledged in court today were wrong.” Flynn also said that he had agreed to cooperate with authorities “in the best interests of my family and of our country. I accept full responsibility for my actions.” Trump fired Flynn in February, days after the White House was told that he had lied to Vice President Mike Pence about the conversations with Kislyak. Sally Yates, then the acting attorney general, later testified that she warned White House counsel Donald McGahn that she feared that Flynn had exposed himself to possible blackmail by the Russians. Flynn became the fourth individual charged by Mueller’s team. In October, former Trump campaign volunteer adviser George Papadopoulos pleaded guilty to lying to federal agents looking at links between the Trump campaign and Russian officials. In addition, former Trump campaign manager Paul Manafort and associate Rick Gates were indicted on charges that included money laundering, income tax evasion and lying to federal investigators. Both Manafort and Gates have pleaded not guilty. “This is the second guilty plea to come from the Trump orbit this year while two other sets of charges are pending against the president’s former campaign manager and a key aide,” Rep. Dina Titus, D-Nev., said in a statement Friday. “President Trump’s recklessness continues to parade itself in front of the