Top U.S. defense officials have recommended that President George W. Bush  withdraw one combat brigade from Iraq but not until early next year, Pentagon sources said on Thursday. A U.S. Army combat brigade has 3,000 to 5,000 troops. The United States now has 15 combat brigades in  Iraq as well as many other units, making a total of more than 140,000 troops. Any cut in Iraq would allow the United States to increase forces in Afghanistan, where commanders have called for more troops to combat rising violence by Islamist militants from al Qaeda and the Taliban. The  United States has some 33,000 troops in Afghanistan. A Pentagon spokesman said he could not discuss details of the recommendations and administration  officials cautioned that Bush had not yet approved any course of action. "The president is now considering his options," White House spokeswoman Dana Perino told reporters. While violence in Iraq has dropped dramatically in the past year, the proposed cutback is smaller than some analysts had predicted, reflecting the desire of Army Gen. David Petraeus, the top commander in  Iraq, not to jeopardize security gains. Three Pentagon sources said that Petraeus had agreed to shift from 15 brigades to 14. Two  sources said the change would not take place until early next year. One source said the recommendation also included other, smaller units but did not elaborate. Bush heard the Pentagon's recommendations on Wednesday in a videoconference with Defense Secretary  Robert Gates and Adm. Mike Mullen, the chairman of the U.S. military's Joint Chiefs of Staff, officials said. "Secretary Gates and Chairman Mullen presented President Bush with their recommendations on how many additional forces could be safely taken out and how soon," Pentagon press secretary Geoff Morrell said. He said Gates and Mullen also presented the views of Petraeus and Army Lt. Gen. Martin Dempsey, acting head of the U.S. military headquarters for operations in the Middle East, and all were "fundamentally in agreement."