U.S. President Barack Obama made a surprise visit to Afghanistan on Friday, spending a brief four hours at Bagram Air Base. While warning of “difficult days ahead,” Obama nonetheless told some 3,800 U.S. troops they were winning the war in Afghanistan. “You’re achieving your objectives, you will succeed in your mission,” Obama said. “We said we were going to break the Taliban’s momentum. That’s what you’re doing.” A planned trip to Kabul to meet with Afghan President Hamid Karzai was scuttled by inclement weather. It was instead replaced with a 15-minute phone call.