According to the search results, General Mark Milley retired from his position as chairman of the Joint Chiefs of Staff on September 29, 2023, after a four-year tenure. He gave a speech on his last day, in which he said that U.S. troops take an oath to the Constitution and not a "wannabe... dictator," which was seen as an apparent swipe at former President Donald Trump. Milley was hailed by President Joe Biden as a sage advisor and as a warrior who served in combat zones from Afghanistan and Iraq to Panama and Haiti. Milleys tenure included the killing of Islamic State head Abu Bakr al Baghdadi in 2019 and providing military assistance to Ukraines defense against the invasion by Russia in February 2022.