Qari Yousef Ahmadi, a Taliban spokesman, claimed in a telephone interview that U.S. forces target civilians "because they are here to kill all Afghans," not just insurgents. He denied that Taliban fighters mingled with civilians in the May 4 incident.
A recent United Nations report says airstrikes accounted for 64% of the 828 civilians killed last year by U.S. or Afghan government forces. About 1,160 civilians died at the hands of the Taliban or other insurgents.
"People are very angry, because these things happen over and over again," Watandar said. "They don't trust the Americans when they say they don't do this on purpose and they have ways to keep it from happening again."
Air Force commanders and pilots say they have not been given new procedures as a result of the renewed focus on civilian deaths. But they have received a clear message that finding ways to reduce such mistakes is paramount, particularly because the Taliban uses such incidents for propaganda purposes.
"There are additional changes that I think we're going to clearly have to make to ensure that we do absolutely everything to make sure civilian casualties are eliminated, if possible, or certainly minimized in every situation," Adm. Michael G. Mullen, chairman of the Joint Chiefs of Staff, said Thursday.
But air supremacy is essential. Without it, thinly stretched ground forces would not have the latitude to pursue the Taliban into remote, rugged areas where they are more prone to be ambushed and cut off.
Insurgents "know air power is something they can't defend," Kwast said. "If they could, they would have the freedom of movement and maneuver to win."
Ground commanders say that before any airstrike is authorized, they work with pilots and Air Force controllers to locate friendly forces, civilians and insurgents. At the same time, commanders back at bases talk to them by radio while watching video feeds from satellites or drones.
When an airstrike is approved, the ground controller can give pilots a "nine-line," a detailed set of instructions that includes target coordinates, the type of weapon to be used, the angle of attack and any restrictions.
The ground commander is in charge, but Air Force controllers and pilots may refuse to fire if they believe rules of engagement might be violated. They may also abort if they see a sudden change, such as insurgents darting into a home.
Only the controller, not the ground commander, can tell the pilot that he is "cleared hot," or cleared to fire.
"We own those weapons when they come off the airplane," said Capt. Ryan McLean, 31, an A-10 Warthog pilot. "If something goes wrong with that weapon, then we are held accountable, even if that ground commander was on the radio screaming for it."
Capt. Terry Gable, 28, who flies an F-15, said pilots are trained to avoid using their weapons if possible. They make low passes or launch nonlethal targeting rockets to try to force insurgents to stop firing. The intent is to avoid accidental killings of civilians or friendly forces.
"It's not all about dropping bombs or shooting the weapons," Gable said. "We go through multiple checklists to make sure the ground guys and us have done everything to make sure buildings are cleared of civilians. And only as a last resort are we going to go kinetic [fire weapons] in order to end contact."
So-called preplanned air missions are carefully vetted in advance, but the decision-making speeds up when fighter pilots are suddenly called in to support troops under fire. The majority of civilian deaths from airstrikes come during such "troops in contact" missions, when pilots, controllers and commanders are faced with rapidly changing conditions and life-or-death decisions.
"Human beings under great stress, under the fear of death, make mistakes," Col. Kwast said. "If you do not do this perfectly, you will kill a lot of coalition forces. They'll be forced to take risks and die because they were not allowed to defend themselves. That's exactly what the enemy wants."
Pilots say the issue is not the procedures, but making sure that they are followed scrupulously. They say that after each mission, they spend several hours discussing every detail that went right or wrong, probing for errors. Internal procedures are refined constantly.
Kwast said adhering to procedures every second of every mission is crucial.
"The trick is to have processes and procedures so rigorous and so defined that you minimize mistakes without tipping the balance so that you kill more Americans," he said.
"That is the million-dollar question. And we deal with that every mission."
Times staff writer Julian E. Barnes in Washington contributed to this report.