Afghan Cop Kills 2 US Troops Killing is 6th 'green-on-blue' attack in 2 weeks By Mark Russell, Newser Staff Posted Aug 17, 2012 4:18 AM CDT 19 comments Comments An Afghan policeman stands guard at a checkpoint in Kabul. (AP Photo/Musadeq Sadeq) (Newser) – Two US soldiers were killed in Afghanistan this morning by an Afghan police officer, the sixth such "green on blue" killing in the past two weeks, reports the AP. One Afghan police officer was also seriously wounded in the attack. The attacker, who had been recruited by the village defense just five days earlier, was shot and killed immediately after slaying the American servicemen. US forces had come to the village to train local police officers. Meanwhile, Taliban leader Mullah Mohammad Omar has called on militants to avoid killing civilians, in the wake of Tuesday's onslaught of suicide bombings, which killed 63 people around Afghanistan and injured hundreds, reports Reuters. Insurgents should "employ tactics that do not cause harm to life and property of the common countrymen," wrote the reclusive leader in a seven-page letter, in which he also boasted of his fighters' ability to infiltrate Afghanistan's security forces.