WASHINGTON — The United States is speeding up its military withdrawal from Iraq, sending 4,000 more troops home next month, the top American commander there says.

The reduced number of troops in Iraq — from 124,000 to 120,000 by the end of October — marks the latest U.S. step in winding down the six-year war. The reduction was to be announced today by Army Gen. Ray Odierno.

"We have already begun deliberately drawing down our forces — without sacrificing security," Odierno said in a statement he was to deliver to the House Armed Services Committee.

The panel's chairman, Rep. Ike Skelton, said adjustments "in Iraq will not be easy for us or, I suspect, for the Iraqis." He called moving troops and equipment out of Iraq a large challenge.

"The war in Iraq is coming to a close, but my suspicion is that these transitions will take years to work through," Skelton, D-Mo., said in a statement released shortly before the hearing began.