The stunning headline out of Afghanistan today for NATO soldiers members of the US led coalition were shot dead not by a sniper in the hills. But by an Afghan soldier trained to fight right alongside... See More
The stunning headline out of Afghanistan today for NATO soldiers members of the US led coalition were shot dead not by a sniper in the hills. But by an Afghan soldier trained to fight right alongside them and a new report says this is becoming an alarming vulnerability for American troops. Here's ABC's Martha Raddatz. Today the US military acknowledged that more -- more American and coalition forces are being gunned down by the very Afghan troops they are fighting along side. More than sixty coalition forces have been killed since 2007. David Broder was one of them the fighter pilot who leaves a wife and two young children. Murdered with eight others last year by an Afghan veteran who said he wanted to kill Americans. The US military says they do not believe this is a systemic problem. As the head of NATO today called these incidents terrible but isolated. But it classified study comes to the opposite conclusion saying the shootings are clearly not rare or isolated. And may be unprecedented. Between allies in modern military history. US is paying twelve billion dollars this year alone. Train Afghan forces at a base we recently visited. The only thing that they really need -- towards is getting the -- working this walking out but in this study Americans described Afghan soldiers as cowardly incompetent. Pot smoking murderous radicals and Afghans calling the Americans. Violent reckless arrogant bullies. Such strong words Diane but the reality that Afghan soldiers who we are training -- their weapons on Americans and our allies is truly horrifying so what does all this say about the goal of getting out -- 2014 turning it over to the Afghan soldiers. Well it is a setback in building Afghan army and that's what has to happen for Americans to leave although this is obviously not completely derailed. I'm Martha Raddatz reporting from Washington thank you mark.
This transcript has been automatically generated and may not be 100% accurate.