Trump, who often likes to build drama and suspense by teasing his decisions, told reporters at the White House that he will make the announcement at the Army-Navy game in Philadelphia, where he is expected to do the coin toss.
“I can give you a little hint: It will have to do with the Joint Chiefs of Staff and succession,” he said.
He did not make clear whether he was referring to successors to the chairman and vice chairman of the Joint Chiefs of Staff or to any of the five other officers who are members of the Joint Chiefs. Under normal circumstances the successor to the chairman, Marine Gen. Joseph Dunford, would not be selected until next year, given that he is due to serve until Oct. 1, 2019.
Dunford was nominated to the post in 2015 by former President Barack Obama. Trump nominated him for a second two-year term last year.
The vice chairman of the Joint Chiefs is Air Force Gen. Paul Selva, whose term expires in July 2019.
The other members of the Joint Chiefs are the heads of the Army, Navy, Marine Corps and Air Force, and the head of the National Guard.
Gen. Mark Milley, the Army chief of staff, is due to finish his term next summer, as are Adm. John Richardson, the chief of naval operations, and Gen. Robert Neller, the commandant of the Marine Corps. Gen. David Goldfein began his term as Air Force chief of staff in 2016.