Ten NATO troops, including seven Americans, were killed in Afghanistan Monday in the worst day for coalition casualties this year. An IED killed five of the Americans in eastern Afghanistan, while small-arms fire and a roadside bomb killed two in the south. An American contractor also died Monday when three men blew themselves up at a Kandahar police training center. In the coordinated attack, one man tried to drive his car through the training center’s perimeter wall as two others, wearing suicide vests, tried to enter the compound on foot. Police fired at the men, who exploded before they got inside. The blast wounded three police officers.