The Americans had a cordial conversation and cracked a few jokes with their Afghan comrades during the Saturday afternoon patrol in Wardak province. The Afghans offered the Americans tea. Then, according to a U.S. military official, an Afghan soldier, without warning or provocation, raised his weapon and opened fire - mortally wounding the senior American on the patrol.
In a war in which insider attacks have become commonplace, what happened next made the incident extraordinary, the American official said. Another Afghan soldier at the checkpoint opened fire on the Americans, killing a U.S. civilian contractor and wounding two other American soldiers. Soon, Afghan soldiers and possibly insurgents began firing at the Americans from several directions.
NATO officials initially described the deadly episode as an insider attack but later said they had not yet classified it as such because of suspected insurgent involvement. A top Afghan military official denied that what took place was an insider attack and said the shooting was caused by a misunderstanding.
A preliminary military report, however, has concluded that the gunfight began only after an Afghan soldier opened fire on U.S. troops, according to the American official, who spoke on the condition of anonymity.
"What sets this apart is that there were multiple attackers from multiple positions and there was zero provocation," said the official, who had access to the report but was not authorized to speak for the record. "Typically we are talking about a single gunman who acted in a somewhat rogue fashion, but in this case we are talking about an entire Afghan army unit and a large loss of life on both sides."
Insider attacks have become the leading threat to the U.S. military's effort to wind down the war by the end of 2014, leaving behind a local force capable of protecting the fragile Afghan state. Before Saturday's incident, Afghan security forces had killed at least 51 NATO troops this year in 37 attacks, up from last year's 37 deaths in 21 attacks.
U.S. military officials say roughly 25 percent of insider attacks have been linked to insurgent groups. They say a large number have stemmed from personal disputes.
In unusually poignant remarks, the top U.S. commander in Afghanistan said over the weekend that he was "mad as hell" about insider attacks. "We're willing to sacrifice a lot for this campaign," Gen. John Allen said in an interview with 60 Minutes that was broadcast Sunday. "But we're not willing to be murdered for it."
NATO officials issued a statement late Saturday describing that day's incident as an "apparent insider attack." The next day, NATO's deputy commander, Lt. Gen. Adrian J. Bradshaw, revised that assessment during a news conference in Kabul.
"What was initially reported to have been a suspected insider attack is now understood to possibly have involved insurgent fire," he said, according to a transcript.
Gen. Abdul Raziq, the top Afghan military official in Wardak, denied that one of his men had opened fire unprovoked. The Americans, he said, mistook enemy fire for an insider attack.
"As soon as the American fell to the ground, his colleagues assumed it was a green-on-blue attack and started shooting," the Afghan general said, using a term to describe incidents of fratricide. "I'm really sad that this happened. I'm sad about the American and Afghan deaths. But I'm relieved it wasn't another green-on-blue attack."
The U.S. military official familiar with the probe said that account is wrong.
The patrol was one of the first for the American platoon since a temporary suspension of most joint operations was announced in mid-September because of concern about a heightened risk of insider attacks. The restriction was implemented after an online video depicting Islam as a barbaric religion triggered unrest throughout the Muslim world. Defense Secretary Leon E. Panetta announced Thursday that most joint operations would resume.
The U.S. platoon began patrolling at 4 p.m. just north of the village of Sisay in the mouth of the Tangi Valley, a Taliban stronghold. The roughly 20 Americans on the patrol stopped at an Afghan checkpoint to collect biometric data, including fingerprints and iris scans, from civilians. Such data are routinely compiled so they can be cross-referenced against evidence collected at attack sites and a database of suspected insurgents.
Comment: In other words, Afghan civilians are constantly terrorised by U.S. soldiers looking for
An Afghan soldier fired the first shot as the data were being collected, the U.S. military official said. Three Afghan soldiers were killed and several were injured in the ensuing gunfight.
"The U.S. soldiers had always been on good terms with them," said the American military official, who disputed the suggestion that the shooting was sparked by a misunderstanding.
The official said he could not rule out the possibility that the Taliban had used the Afghan troops to set up an ambush, but he said there was no intelligence to support that scenario. NATO and the Afghan army are carrying out a joint investigation.
The identities of the Americans killed have not been released.
NATO officials have argued that their relationship with the Afghan security forces remains fundamentally strong despite the rise in insider attacks.
"If you visit people who are working together closely with thousands of interactions every day, you see strong, trusting relationships resulting in cooperative operations delivering success every day in the field," Bradshaw, the deputy NATO commander in Afghanistan, said during Sunday's news conference.
Though the ban on joint patrols has been nominally lifted, some commanders are proceeding with great caution. In the military coalition's eastern command, for example, U.S. soldiers must now submit a memorandum to their division before each patrol assessing the risk of fratricide.
"The relationship is definitely strained at this point," said the American official familiar with the investigation. "U.S. soldiers have to be much more on guard if they are asked to work with them and have to thoroughly assess risk if we are to continue to do operations with them."
Kevin Sieff in Mazar-e Sharif contributed to this report.