WASHINGTON (AP) - Sen. John Warner, a prominent Republican on military affairs, urged President Bush on Thursday to start bringing some troops home from Iraq by Christmas. Such a move would send a powerful warning to the Baghdad government that time is running out, said Warner, R-Va. Warner said the president next month should announce the withdrawal of a certain number of troops to send a "sharp and clear message throughout the region and the United States" that the commitment in Iraq is not open ended. "We simply cannot as a nation stand and continue to put our troops at...