Afghan troops kill 70 U.S. soldiers since 2007

Often reports of Afghan soldiers killing U.S. trainers simply do not include what actually happened. The Pentagon reported the recent killing of Lance Cpl. Edward Dycus that he died “while conducting combat operations.”.
An Afghan soldier shot Dycus in the back of the head on Feb. 1 while he was standing guard at a joint Afghan-US base in Helmand province. Dycus's parents however received a note that he was killed by an Afghan soldier.
In the last six weeks alone 7 U.S. soldiers have been killed by their Afghan partners. Following the burning of the Korans at Bagram Air Base an Afghan killed two U.S. soldiers on Feb. 23.
In this instance the Pentagon also disguised what actually happened. The official report said that the soldiers died of "wounds suffered when their unit came under small arms fire."
The U.S. military had ample warning of what was going to happen. In May 2011 Jeffrey Bordin a behavioral scientist with the U.S. army in Afghanistan issued a report. Bordin said there was a crisis of trust between U.S. and Afghan forces. He said this could result in an unprecedented number of killings between allies in modern history.
As one would expect the reception of this report was very harsh. But even ISAF admits that ten months after the report the numbers of those killed by Afghan forces is still quite high. The other side of the coin is that there are probably many cases where U.S. troops kill Afghans out of revenge. In fact Robert Fisk suggests that revenge killings by U.S. troops is a real danger recognized by commanders and that the recent Kandahar killings may be revenge killings. See this article. For more see this article.