A flurry of changes in the Pentagon’s top ranks is underway as President Donald Trump elevates longtime allies in moves that critics say sends a signal of turmoil in the leadership of the U.S. military just after a contentious election.

A day after Trump fired Pentagon chief Mark Esper by tweet, two senior officials stepped down on Tuesday, as did Esper’s former chief of staff. James Anderson, the acting deputy under secretary of defense for policy, didn’t give a reason for his departure in a resignation letter to the president, but praised policies put in place during the Trump administration. He had been in his current post only since June.

Later in the day, the Pentagon said Under Secretary of Defense for Intelligence and Security Joseph Kernan resigned in what he called a planned departure. In an email to staff, Kernan said "I leave knowing that our efforts will continue given your unrelenting dedication to the security of this Nation.”