In a holiday season pep talk to US troops, Defense Secretary Donald H. Rumsfeld said an early withdrawal from Afghanistan or Iraq would lead to new terrorist attacks on Americans at home. Rumsfeld spoke Thursday to several hundred soldiers in a heated tent at this base that serves as the main airfield for US forces in Afghanistan. "If we were to withdraw from Afghanistan precipitously, or from Iraq, the terrorists would attack us first somewhere else and then they would attack us at home, let there be no doubt," he said. Rumsfeld thanked the soldiers for their service. "The momentous changes here could not have happened without your service," he said.