In a tweet (of course), Donald Trumphas announced he has selected Gen. Mark A. Milley, chief of Staff of the Army, as the next chairman of the Joint Chiefs of Staff: "I am pleased to announce my nomination of four-star General Mark Milley, chief of Staff of the United States Army -- as the chairman of the Joint Chiefs of Staff, replacing General Joe Dunford, who will be retiring," the president tweeted. "I am thankful to both of these incredible men for their service to our Country!"

Gen. Mark A. Milley, the Army's chief of staff (right) was nominated to succeed Marine Corps General Joe Dunford (left) as chairman of the Joint Chiefs of Staff. President Donald Trump tweeted the nomination Dec. 8, 2018. (Photo credit: Petty Officer 2nd Class Dominique Pineiro)

If confirmed by the Senate, Milley would succeed Marine Corps Gen. Joe Dunford, who has served in the position since September 2015. Dunford will step down in September 2019. Trump said the date of transition is "to be determined." Milley would be the 20th man to hold the position since General of the Army Omar N. Bradley in 1949.

Milley, a Massachusetts native and Princeton graduate, has served as the Army's 39th chief of staff since 2015. Previously, he commanded U.S. Army Forces command at Fort Bragg, North Carolina. He served as commanding general of III Corps, based at Fort Hood, Texas, and earlier as commander of the 10th Mountain Division.