A roadside bomb exploded in southern Afghanistan Tuesday, killing four U.S. troops and marking a grim new benchmark in the war against the Taliban that began in 2001. So far this year, 295 foreign troops have died on Afghan soil, making it the deadliest year since the conflict began. The bombing, along with the growing allegations of corruption in the recent presidential election, highlights the worsening situation in Afghanistan, where troops are pressing deep into Taliban territory. The surge of troops under the Obama administration has been especially difficult—Reuters reports that more Western troops have died since March than in the first three years of the war. U.S. military officials are concerned that the discord over the election will only further destabilize the war-torn country.