An Afghan army soldier turned his gun on his NATO colleagues Monday injuring two US troops, officials said, just a day after a local policeman killed three foreign trainers in a similar attack. The incident in the northern province of Faryab is the latest in a series of so-called “green-on-blue” attacks involving members of the Afghan national security forces targeting their NATO allies. “An Afghan army soldier opened fire on US soldiers inside a military base… and injured two US soldiers. The attacker was killed in return fire,” Faryab’s deputy provincial governor Abdul Satar Barez told AFP. NATO’s US-led International Security Assistance Force, to which most of the 130,000 Western troops in Afghanistan are attached, confirmed the incident but refused to give information on casualties.