(Newsroom America) -- An exchange of gunfire between American troops and allied Afghan soldiers left one U.S. serviceman dead over the weekend, pushing the number of U.S. troops killed in the Southwest Asian country to 2,000.
The U.S. death toll has climbed in recent months as so-called "blue-on-green" attacks - in which some Afghan troops turned their weapons on their American allies - have ramped up.
Such attacks against U.S. and NATO forces have left many analysts questioning whether Afghan forces will be able to stand on their own after the coalition withdraws its forces by the end of 2014.
U.S. military commanders have struggled to counter the tactic of insider attacks, which appear to be influenced by the Taliban, appealing to the government of Kabul to better screen its recruits. The attacks have killed 52 U.S. servicemen this year.
"We have to get on top of this. It is a very serious threat to the campaign," Army Gen. Martin Dempsey, the U.S. Army's top officer, said in response to the attacks.
The top commander of U.S. and NATO forces in Afghanistan, Gen. John Allen, was more direct.
"I'm mad as hell about them, to be honest with you," he told CBS News' "60 Minutes" program Sunday. "It reverberates everywhere across the United States. You know, we're willing to sacrifice a lot for this campaign, but we're not willing to be murdered for it."
The insider attacks are considered the biggest threat to the U.S. exit strategy, analysts have said.
Part of the U.S. draw down has already occurred. The 33,000 troops so-called "surge" troops order to Afghanistan by President Obama in 2009 were all withdrawn by the end of September, leaving 68,000 American troops still remaining.
In all, NATO has 108,000 troops there, down from 150,000 at its peak last year.
© 2012 Newsroom America.