The decision affects some 47,000 soldiers in Baghdad.
"We did make a command decision, that would be me, that we couldn't do any more environmental leave, R&R, after Jan. 31," said Dempsey, commander of the Wiesbaden, Germany-based 1st Armored Division. "We did that principally because we have a mission to accomplish in transitioning the city of Baghdad over to the unit following us."
In a media briefing in Baghdad Monday Dempsey said the 1st Armored Division would be leaving "over the next 90 days," Stars and Stripes reported.
R&R continues for other troops in Iraq, U.S. Central Command spokesman Maj. Pete Mitchell said.