The senior commander for Special Operations forces in Afghanistan has suspended training for all new Afghan recruits until the more than 27,000 Afghan troops working with his command can be re-vetted for ties to the insurgency.

The move comes as NATO officials struggle to stem the tide of attacks on NATO forces by their Afghan colleagues. The attacks, which have killed 45 troops this year, have forced NATO officials to acknowledge a painful truth: Many of the incidents might have been prevented if existing security measures had been applied correctly.