Gen. David Allvin, the Air Force’s chief of staff, will retire on Nov. 1, two years into his four-year term, the Air Force announced,

Air Force chief of staff Gen. David Allvin announced he will retire in November, just two years into what is usually a four-year term as Air Force Chief of Staff.

One senior Air Force officer expressed surprise at the announcement, saying there were no signs or rumors of his stepping down so early. “I don’t know what this is about — he’s a great leader and this is going to be another transition in the building that has seen plenty of it recently.”