That the war in Afghanistan has been unwinnable has been obvious to most outside analysts since well before the so-called surge of 2009. Now, the United States government has finally admitted the obvious in deeds if not words.

Following the murder of six NATO troops in yet another "green on blue" attack in which Afghan soldiers supposedly fighting on our side killed NATO troops, the coalition has all but ended combined operations with Afghan army and police forces at the tactical level, requiring general officer approval for exceptions.

While spokesmen insisted that "we're not walking away" from the training and advisory mission that is the ostensible reason for continued Western presence in Afghanistan eleven years into the fight there, that statement rings hollow. As American Security Project Central and South Asia specialist Joshua Foust puts it, "The training mission is the foundation of the current strategy. Without that mission, the strategy collapses. The war is adrift, and it's hard to see how anyone can avoid a complete disaster at this point."

Three years after doubling down on an unachievable mission, trust between NATO and Afghan forces is at an all-time low. Already this year, there have been thirty-six of these insider attacks, killing fifty-one NATO troops, most of them Americans.

Even before the latest policy announcement, Joint Chiefs chairman Martin Dempsey acknowledged the severity of the problem, declaring, "You can't whitewash it. We can't convince ourselves that we just have to work harder to get through it. Something has to change" and admitting that "It is a very serious threat to the campaign."

The NATO strategy, articulated at the November 2010 Lisbon Summit, is for Afghan forces to assume "full responsibility for security across the whole of Afghanistan" by the end of 2014. How that's going to be possible when we can't even trust them not to shoot their trainers is unfathomable.

Nor is the spate of fratricidal attacks the only obstacle. The Taliban, whose "momentum" the surge was supposed to stop, seems to be getting more bold by the day. On Friday, militants in U.S. Army uniforms breached Camp Bastion, the British air base in Helmand Province, where they killed two American marines and were able to destroy six U.S. Marine Corps Harrier jets and damage two others.

And at least thirteen people were killed this week in a suicide bombing at Kabul's airport. A militant group called Hezb-i-Islami claims credit for the attack and says it's in retaliation for the controversial video that is ostensibly the spark for an outburst of murder and mayhem around the region in recent days, including the attack that killed U.S. ambassador to Libya Christopher Stevens.

Speaking of campaigns, one wonders what it will take for the debacle in Afghanistan, which has claimed 2,121 American lives, 257 so far this year, to become part of the discussion between the men vying for the post of commander-in-chief. Perhaps Mitt Romney, who has had one debacle after another on the campaign trail the past few days, will seize the opening to announce his support for rapid withdrawal.

More likely, however, both he and President Obama will continue to pretend that American soldiers and marines aren't dying in Afghanistan for a cause that's long since been lost.

James Joyner is managing editor of the Atlantic Council.

Image: The U.S. Army