BAGRAM AIR BASE, AFGHANISTAN — When Afghan parliament member Obaidullah Helali went to visit his constituents in the village of Garani last month, they confronted him with clubs and stones.
It was three days after a U.S. airstrike killed dozens of civilians in the remote settlement in the western province of Farah. Enraged villagers threatened to beat Helali and other officials and asked why the Afghan government couldn't protect them -- not from the Taliban, but from the U.S. military.
"If the Americans don't stop these kind of accidents, the people will never believe the government will keep them safe," Helali said.
But experiences such as the fateful May 4 airstrike show that halting civilian deaths will not be easy. Fighter pilots and air controllers at the main U.S. air base here, near Kabul, the Afghan capital, say that even the most comprehensive safeguards can fail under the stress and confusion of combat against an enemy that they say often uses civilians as human shields.
The mounting death toll of Afghan civilians from U.S. airstrikes has unleashed a tide of resentment and fury that threatens to undermine the American counterinsurgency effort. From President Obama to the new U.S. commander in Afghanistan, Army Gen. Stanley A. McChrystal, American officials have made the reduction of civilian deaths a top priority as they revamp their strategy.
McChrystal, who took command this week, told Congress that the measure of success in Afghanistan should be the number of civilians protected, not the number of insurgents killed. Reducing civilian casualties is "essential to our credibility," he said.
The U.S. military employs a lengthy set of precautions, including written rules of engagement and multiple levels of approval before bombs can be dropped or missiles launched.
To gauge each mission's risk to civilians, a collateral damage estimate, or CDE, is prepared.
Yet civilian deaths continue to mount. U.S. commanders have not specified how they intend to reduce them, except to continue rigorously reviewing and enforcing existing restrictions. But the nature of the war almost guarantees more accidental deaths.
When people make split-second life-or-death decisions, and face what they consider a choice between protecting their compatriots or civilians, the decisions have proved imperfect.
"We have a very smart enemy who understands our weakness," said Air Force Col. Steven Kwast, an F-15 pilot who commands the 455th Air Expeditionary Wing at Bagram.
"And our weakness is the fact that this counterinsurgency is not about killing the enemy," he said. "It's about protecting the civilians of Afghanistan. . . . The enemy is good about drawing us into a dilemma we can't get out of without losing coalition lives."
A preliminary Pentagon investigation of the May 4 incident -- the final report is expected within days -- found that mistakes were made in the fighting that led to the airstrikes.
U.S. Marines called in Air Force and Navy warplanes after the Afghan army and police were attacked by insurgents. One aircraft was cleared to drop bombs but the pilot briefly lost sight of the target while circling to get into position to attack, the preliminary investigative report says. It also questions whether a B-1 bomber strike on a village compound was necessary at one point in the 8 1/2 -hour battle when Afghan forces were not under direct attack.
"In a perfect world, that pilot would have never lost sight, even for a few seconds, of those combatants shooting at our friendlies" and possibly mingling with civilians, Kwast said. "But you have to take the criticism and say, hey, we could have done better."
Marines called in the airstrikes after Afghan army and police forces they were mentoring ignored warnings and went to root out insurgents in the village, where they were ambushed, an American security specialist said in Kabul.
Neither U.S. nor Afghan forces secured the village until two days after the attack, allowing the Taliban to control the area and information about the attack, the security specialist said.
The specialist, who has visited the attack site, said insurgent movements reported by Marines late in the battle might also have included civilians running for cover.
After the attack, the specialist said, the U.S. and Afghan governments made solatia, or condolence, payments. They apologized. And they held a council meeting two weeks later that included Afghan President Hamid Karzai and top U.S. diplomats.
Helali and other Afghan officials say 140 civilians were killed. The U.S. estimates that 26 died.
Abdul Ghafar Watandar, the police chief in Farah province, said in an interview that the final death toll could be 75 to 78. He said some villagers could not come up with confirmed names of family members they claimed were killed. He suspected they were fraudulently seeking condolence payments.