Afghan military official : Recruits must pass background checks and provide government references . Insider operations are sometimes conducted by Afghan soldiers , sometimes by the Taliban . Official : Motives range from emotional stress to being threatened by insurgency . Coalition forces use ` ` guardian angels , '' or armed troops who appear at designated times and at night .
Afghan defense official : Recruits must pass background checks and provide government references . Insider attacks are sometimes committed by Afghan soldiers , sometimes by the Taliban . Official : Motives range from emotional stress to being influenced by insurgency . Coalition forces use `` guardian angels , '' or armed troops who guard at meal times and at night .