A spokesman for the U.S. military advisory mission here, Lt. Col. Dave Butler, said in a statement that Afghan security officials requested “precision air support” during heavy fighting and that U.S. military personnel had worked with Afghan coordinators. The coordinators “confirmed that the areas were clear of friendly forces,” he said. “Unfortunately, they were not, and a tragic accident resulted.”
U.S. officials are “examining the miscommunication to ensure it is not repeated,” Butler said. “We regret this tragic loss of life of our partners.”
Afghan officials in Kabul and Helmand gave conflicting information on the number of casualties, saying that between eight and 18 Afghan personnel were killed and that 14 others were wounded. They said the incident, which took place during a ground battle on the Kabul-Kandahar highway, was under investigation.
The Taliban said in a statement that U.S. forces were behind the strikes, but the Helmand governor’s office said it was not clear whether Afghan or foreign forces had carried them out.
The incident occurred amid the widespread combat between Taliban fighters and U.S.-backed Afghan forces that has gone on for months and caused heavy casualties among Afghan troops and civilians.
The Taliban launched its annual spring offensive in March and has continued aggressive attacks since last week, the start of Ramadan, the Muslim month of fasting and prayer. The Taliban surge is seen as a means to gain leverage in ongoing peace talks with the United States.
Errant airstrikes such as occurred in Helmand have been relatively rare during the years of conflict here, but Thursday’s incident bore a striking resemblance to a recent occurrence in southern Uruzgan province in March, when at least five Afghan soldiers were killed and 10 wounded in U.S. airstrikes.
In that case, Afghan defense officials said, the soldiers had been patrolling near a checkpoint when they were attacked from the air. “The attack was caused by lack of proper coordination,” a defense official told the Reuters news agency at the time.
In a statement about the March air attack, the U.S. military said its forces had conducted “precision self-defense airstrikes on people firing on Afghan and American forces” who were conducting a ground operation near an Afghan army checkpoint.
Deadlier incidents have occurred. More than 40 civilians were killed in aerial attacks in October 2015 in the northern city of Kunduz while a ferocious battle was underway against Taliban insurgents for control of the area. A U.S. AC-130 gunship attacked a hospital run by the charity Doctors Without Borders, killing 42 people, after receiving confused or unclear target information from Afghan ground forces.
The incident provoked an angry outcry from the Afghan public and led to a major investigation by U.S. military officials. Since then, U.S. military commanders have made repeated efforts to improve battlefield and air coordination with their Afghan counterparts.
Sharif Hassan and Sayed Salahuddin contributed to this report.