US Marine guards at the American embassy killed four Afghan soldiers by mistake. Some Afghan soldiers were taking unloaded AK-47 rifles from a truck, and moving them into an Afghan army building across the street from the embassy. In the course of doing this, one or more of the Afghan soldiers pointed one of the AK-47s at the Marines, who promptly opened fire, killing four of the Afghan soldiers. American troops are taught to never point a weapon at someone unless you intent to shoot them. Afghans like to point weapons at people, without the intention of shooting. Think of it as a form of greetings. But sometimes they do open fire. It's a form of culture clash.