An airstrike near the village of Akwanaja earlier this year shows how Nigeria’s military, which is backed by the United States and other powers, has repeatedly conducted attacks from the air that have killed civilians. Engaged in a war with Islamist insurgents in the northeast, the air force is often called upon to tackle criminal activity like banditry in areas far from the conflict zone.

The only thing Ibrahim Muazu remembers is “hearing a noise from the sky.”

“After that,” the 27-year-old Nigerian herder says, “I woke up lying in my own blood. There were so many dead.”

Dozens of ethnic Fulani herders were killed in a January 24 aerial bombing in the central Nigerian state of Nasarawa as they were unloading cattle retrieved from authorities in a neighbouring state, according to witnesses, local leaders and detailed complaints describing the day’s events. The livestock had been seized days earlier after the herders allegedly violated local grazing restrictions.

Images from social media and local news reports at the time show the bodies of young men, some mutilated, lined up on a white sheet awaiting burial. The attack took place far from any active conflict, said witnesses, including two who said they were there at the time and two who arrived afterward.

The airstrike near the village of Akwanaja provides a stark example of a broader trend: The nation’s military, which is backed by the United States, the UK and other non-Western allies in a long war against Islamist insurgents in the northeast, has been unleashing deadly aerial assaults for years in other parts of the country.

Beyond the warzone in the northeast, the airforce has been called on to tackle the growing threat in Nigeria’s northwest and central region posed by armed criminal gangs that spray villages with bullets and carry out mass kidnappings. The aircraft have repeatedly killed civilians and people not actively engaged in armed conflict.

An analysis of violent incidents documented by the Armed Conflict Location & Event Data Project (ACLED), a US-based crisis monitoring group, found that more than 2,600 people had been killed in the last five years in 248 airstrikes by the Nigerian Air Force outside the three north-eastern states engulfed in war.

Most victims are identified in the database as belonging to “communal militia,” a broad term that in Nigeria can include anyone from community self-defence groups to criminal gangs known locally as bandits. The incidents documented in the database were not independently confirmed by Reuters.

More than 90 of the victims were civilians, according to the ACLED data, which is based on reports from sources including news organisations, human rights groups and local authorities. That tally does not include those killed in the January 24 attack, because, drawing on initial information contained in news reports, ACLED listed the attack as caused by a landmine, remotely detonated explosive or improvised device.

But witnesses, among them community leaders, have said the herdsmen were hit from the sky, either from a plane or drone.

On Tuesday, the US-based non-profits Human Rights Watch reported that in response to its own investigation of the incident, the Nigerian Air Force for the first time acknowledged responsibility for the attack.

According to the report, Air Commodore D.D. Pwajok explained in a May 17 letter to the rights watchdog that it carried out the strike based “on credible intelligence,” specifically surveillance footage showing the movement of “suspected terrorists” who had converged around a vehicle.

The letter said the Nigerian Air Force is committed to human rights and “further deliberations” on the issue, according to the report.

The non-profit said in its report that the air force did not reply to key questions, including how the information was verified and whether any measures had been taken to avoid civilian casualties.

“The absence of details raises the question of whether the air force carried out the airstrike based on mere suspicion,” Human Rights Watch said.

We were unable to independently confirm that finding. The Nigerian Air Force, defence headquarters and Ministry of Defence did not respond to the news agency’s requests for comment on the Jan. 24 airstrike or its use of airpower generally outside the warzone.

The deadly airstrike came amid renewed worries among key US lawmakers about weapons deals in recent years in which hundreds of millions of dollars in military hardware has been approved for sale to Nigeria despite its tarnished human rights record.

“I remain concerned about the Nigerian Air Force’s record of civilian casualties – but particularly regarding the seeming lack of accountability for these incidents,” California Congresswoman Sara Jacobs, a Democrat and member of the House Foreign Affairs Committee, said on Monday in a statement to Reuters. “I urge a full investigation of this strike and amends for those impacted.”

So far, there is no evidence that any US-supplied aircraft or weapons were used in the January 24 attack or any other involving non-combatant deaths.

In the last five years, more than 2,600 people have been killed in airstrikes, like the one near Akwanaja village, by the Nigerian Air Force outside the conflict zone in the country’s northeast, according to an analysis of data provided by ACLED, a US-based monitoring group. The satellite image, taken by Planet Labs PBC on May 30, 2023, shows where some of the Fulani herdsmen killed in an aerial attack on January 24 were buried.

The US State Department and the Pentagon had no immediate comment about the airstrike or the US relationship with the Nigerian Air Force. The White House declined to comment.

In Nigeria itself, civilian deaths in airstrikes have come under scrutiny. Three months before the strike in Nasarawa, a statement from the chief of air staff, Air Marshal Oladayo Amao, said that a committee had been set up to “compile all allegations of accidental airstrikes on civilians as well as review the circumstances leading to such strikes.”

The purpose, it said, was to “mitigate future instances of collateral damages on civilians.” Nonetheless, Amao credited airstrikes with curtailing the activity of “miscreants who want to destabilise the nation.”

Representatives of the administration of former President Muhammadu Buhari, under whose leadership the January 24 bombing occurred, did not respond to a request for comment for this story. Nor did the administration of current President Bola Tinubu, who took office at the end of May.

Before now, neither the Nigerian government nor the military had provided any public explanation for what happened on January 24. Outraged and bereaved community members said they have been left to speculate.

In interviews, Muazu and another witness injured in the January 24 attack described the incident as an unprovoked assault on people peacefully going about their business.

“There was no fighting,” said Muazu, who specified his injuries as a broken leg and hand, a dislocated back and a “seriously wounded” neck. Nine of his family members died, he said.

Lamido Sanusi, a Fulani and former emir of Kano, Nigeria’s second-highest Islamic authority, explained that the herdsmen and their advocates would not relent in pressuring the government for answers.

“We suspect there will be an attempt to sweep this under the carpet and have it forgotten,” said Sanusi, also Nigeria’s ex-central bank governor.

But the community, he said, “will push this matter as far as we can go for redress, within the bounds of the law.”

The January 24 attack has drawn limited international attention, especially in the United States. At least one previous airstrike caught the eye of US Congress members and human rights groups, however.

In 2017, Nigeria’s airforce was heavily criticised for bombing a camp for displaced people while on a mission targeting Islamist insurgents in Rann, in the warzone near the Cameroonian border.

The airstrike, which Nigerian officials described as a mistake, killed at least 90 people, the majority of them women and children, according to medical charity Medecins San Frontieres (MSF), which had teams in the camp at the time. Residents and community leaders said as many as 170 died.

• A Reuters report