A misunderstanding resulted in Afghan service members opening fire using small arms and rocket-propelled grenades on a patrol of their counterparts and American advisers in southern Afghanistan, triggering a battle and U.S. airstrikes that killed at least five Afghan soldiers and injured nine others, officials in Kabul revealed on Wednesday.

Both sides reportedly thought they were fighting Taliban narco-jihadis.

A spokesman for the U.S.-NATO mission declared that the friendly fire did not kill or wound any Americans, Stars and Stripes reports, noting, “It is unclear whether the strikes or the firefight caused the [Afghan] casualties.”

Nevertheless, citing Afghan officials, the New York Times (NYT) notes that the U.S. airstrikes “wiped out” the Afghan Army base where the incident took place, suggesting that the American military may have been responsible for the casualties.

Afghanistan’s defense ministry and the U.S. military acknowledged that that misunderstanding led to a coalition strike in self-defense that struck the Afghan National Army (ANA) checkpoint.

Referring to the friendly fire incident, Sgt. 1st Class Debra Richardson, a spokesman for U.S. military in Afghanistan, told NYT:

This is an example of the fog of war. The U.S. conducted a precision self-defense airstrike on people who were firing at a partnered U.S.-Afghan force. … The Afghan and U.S. partnered force tried to de-escalate the situation but in the fog of war they continued to be fired upon. We are operating in a complex environment, Afghans included, where attacks come from fighters who do not wear their uniforms.

In a statement to Military Times, Lt. Ubon Mendie, a spokesman for U.S. Forces-Afghanistan, added, “The strikes were conducted after Afghan and U.S. forces came under effective small-arms and rocket-propelled grenade fire and requested air support in self-defense.”

Although the Taliban is known to infiltrate the Afghan National Defense and Security Forces (ANDSF) and cause insider attacks by stealing their uniforms and military equipment, there is no evidence of that in connection to Wednesday’s incident.

Stars and Stripes reports:

The firefight was a result of a lack of communication between Afghan forces, a senior Defense Ministry official said, speaking on condition of anonymity to discuss the matter. The Afghan forces and their U.S. advisers were conducting a planned night raid when they approached the Afghan National Army checkpoint near the town of Tirin Kot, the capital of Uruzgan province.

“Our forces on the ground, they didn’t know about this fact, they started shooting,” the unnamed Afghan defense official told the newspaper.

Echoing the anonymous official, Qais Mangal, a spokesman for the Afghan defense ministry, also accused the Afghan checkpoint of firing the first shot.

“The Afghan Army outpost opened fire first on a unit of Afghan and foreign forces headed to a military operation,” the official said.

Nevertheless, NYT quotes Mohammed Karim Karimi, the deputy head of the Uruzgan provincial council, as indicating that it remains unclear who fired first.