WASHINGTON - A military investigation has concluded that American personnel made significant errors in carrying out some of the airstrikes in western Afghanistan on May 4 that killed dozens of Afghan civilians, according to a senior American military official.
The official said the civilian death toll would probably have been reduced if American air crews and forces on the ground had followed strict rules devised to prevent civilian casualties. Had the rules been followed, at least some of the strikes by American warplanes against half a dozen targets over seven hours would have been aborted.
The report represents the clearest American acknowledgment of fault in connection with the attacks. It will give new ammunition to critics, including many Afghans, who complain that American forces too often act indiscriminately in calling in airstrikes, jeopardizing the United States mission by turning the civilian population against American forces and their ally, the Afghan government.
Since the raid, American military commanders have promised to address the problem. On Tuesday, Lt. Gen. Stanley A. McChrystal, nominated to be the American commander in Afghanistan, vowed that reducing civilian casualties was "essential to our credibility."
Any American victory would be "hollow and unsustainable" if it led to popular resentment among Afghanistan's citizens, General McChrystal told the Senate Armed Services Committee during a confirmation hearing.
According to the senior military official, the report on the May 4 raids found that one plane was cleared to attack Taliban fighters, but then had to circle back and did not reconfirm the target before dropping bombs, leaving open the possibility that the militants had fled the site or that civilians had entered the target area in the intervening few minutes.
In another case, a compound of buildings where militants were massing for a possible counterattack against American and Afghan troops was struck in violation of rules that required a more imminent threat to justify putting high-density village dwellings at risk, the official said.
"In several instances where there was a legitimate threat, the choice of how to deal with that threat did not comply with the standing rules of engagement," said the military official, who provided a broad summary of the report's initial findings on the condition of anonymity because the inquiry was not yet complete.
Before being chosen as the new commander in Afghanistan, General McChrystal spent five years as commander of the Joint Special Operations Command, overseeing commandos in Iraq and Afghanistan. Special Operations forces have been sharply criticized by Afghans for aggressive tactics that have contributed to civilian casualties.
During his testimony, General McChrystal said that strikes by warplanes and Special Operations ground units would remain an essential part of combat in Afghanistan. But he promised to make sure that these attacks were based on solid intelligence and that they were as precise as possible. American success in Afghanistan should be measured by "the number of Afghans shielded from violence," not the number of enemy fighters killed, he said.
The inquiry into the May 4 strikes in the western province of Farah illustrated the difficult, split-second decisions facing young officers in the heat of combat as they balance using lethal force to protect their troops under fire with detailed rules restricting the use of firepower to prevent civilian deaths.
In the report, the investigating officer, Brig. Gen. Raymond A. Thomas III, analyzed each of the airstrikes carried out by three aircraft-carrier-based Navy F/A-18 strike aircraft and an Air Force B-1 bomber against targets in the village of Granai, in a battle that lasted more than seven hours.
In each case, the senior military official said, General Thomas determined that the targets that had been struck posed legitimate threats to Afghan or American forces, which included one group of Marines assigned to train the Afghans and another assigned to a Special Operations task force.
But in "several cases," the official said, General Thomas determined either that the airstrikes had not been the appropriate response to the threat because of the potential risk to civilians, or that American forces had failed to follow their own tactical rules in conducting the bombing runs.
The Afghan government concluded that about 140 civilians had been killed in the attacks. An earlier American military inquiry said last month that 20 to 30 civilians had been killed. That inquiry also concluded that 60 to 65 Taliban militants had been killed in the fight. American military officials say their two investigations show that Taliban fighters had deliberately fired on American forces and aircraft from compounds and other places where they knew Afghan civilians had sought shelter, in order to draw an American response that would kill civilians, including women and children.
The firefight began, the military said, when Afghan soldiers and police officers went to several villages in response to reports that three Afghan government officials had been killed by the Taliban. The police were quickly overwhelmed and asked for backup from American forces.
American officials have said that a review of videos from aircraft weapon sights and exchanges between air crew members and a ground commander established that Taliban fighters had taken refuge in "buildings which were then targeted in the final strikes of the fight," which went well into the night.
American troop levels in Afghanistan are expected to double, to about 68,000, under President Obama's new Afghan strategy.
In his previous job as commander of the Joint Special Operations Command, General McChrystal oversaw units assigned to capture or kill senior militants. In his appearance before Congress on Tuesday, he was questioned on reports of abuses of detainees held by his commandos.
Under questioning by Senator Carl Levin, the Michigan Democrat who is the committee chairman, General McChrystal said he was uncomfortable with some of the harsh techniques that were officially approved for interrogation. At the time, such approved techniques included stress positions, sleep deprivation and the use of attack dogs for intimidation.
He said that all reports of abuse during his command were investigated, and that all substantiated cases of abuse resulted in disciplinary action. And he pledged to "strictly enforce" American and international standards for the treatment of battlefield detainees if confirmed to the post in Afghanistan.
Under questioning, General McChrystal also acknowledged that the Army had "failed the family" in its mishandling of the friendly-fire death of Cpl. Pat Tillman, the professional football star who enlisted in the Army after the attacks on Sept. 11, 2001.
A final review by a four-star Army general cleared General McChrystal of any wrongdoing, but punished a number of senior officers who were responsible for administrative mistakes in the days after Corporal Tillman's death. Initially, Army officials said the corporal had been killed by an insurgent ambush, when in fact he had been shot by members of his own Ranger team.