A string of militant attacks in Afghanistan have killed 12 police officers while six civilians died in bombings, authorities said Tuesday. Also, a U.S. service member was killed Tuesday in a gunbattle in eastern Afghanistan, said Col. Wayne Shanks, a spokesman for U.S. forces. And a British Marine died in a hospital in Britain from injuries sustained in a firefight Sunday in southern Helmand province, the British Defense Ministry said. Both NATO troops and Afghan security forces have been suffering heavier casualties in recent weeks. Including the latest deaths, 41 international service members have been killed in Afghanistan so far this month, 27 of them American.