Andrew Caballero-Reynolds | AFP | Getty Images Director of the US Secret Service Randolph Alles speaks during a press conference at the Department of Justice in Washington, on October 26, 2018. President Donald Trump has instructed White House chief of staff Mick Mulvaney to fire U.S. Secret Service Director Randolph Alles, NBC News reported Monday. A White House spokesman did not immediately reply to CNBC's questions. The Secret Service did not immediately provide a comment. The Secret Service chief's ouster comes less than a day after the announcement that Kirstjen Nielsen, Trump's secretary of Homeland Security, was also leaving the administration. Trump tweeted Sunday that Kevin McAleenan, the current commissioner of U.S. Customs and Border Protection, would serve as the acting Homeland Security secretary. Less than a week earlier, federal authorities charged Chinese national Yujing Zhang with illegally gaining entry to Trump's Mar-a-Lago resort in Palm Beach, Fla., slipping past at least five Secret Service agents and making it all the way to the main reception area of the compound. Trump had praised the Secret Service last Wednesday in the wake of the alleged incident. Asked about his confidence in the luxury club's security, Trump said, "I could not be happier with Secret Service. Secret Service has done a fantastic job from day one. Very happy with them." NBC's Pete Williams reported Monday that, according to an administration official, Alles' firing was "not based on any single precipitating event." The decision was made 10 to 14 days ago, the official told NBC \u2014 before the alleged trespass at Mar-a-Lago. CNN first reported the staffing development Monday afternoon, citing administration officials. This is developing news. Please check back for updates.