The letter raises questions about the nature of U.S. involvement in the 2017 attack, including about the circumstances that led to targeting of the displaced persons’ camp; whether corrective action was taken by the Nigerian or U.S. militaries; if AFRICOM or the State Department had knowledge of the U.S. role in the attack; and whether the United States has continued to assist the Nigerian military in airstrikes or ground operations.

“Congress has a critical role to play in ensuring that the United States prevents, mitigates, and responds to civilian harm with transparency and accountability — and that includes harm committed when working by, with and through partners,” said Annie Shiel, the senior adviser for U.S. policy and advocacy at the Center for Civilians in Conflict. “Given that AFRICOM has apparently investigated the strike already, I hope the Defense Department will respond transparently to this inquiry — and to the demands of civil society groups — by publicly releasing the investigation and acknowledging any U.S. role in the strike and its impact.”

In July, AFRICOM spokesperson Kelly Cahalan did not answer The Intercept’s questions about the results of Stokes’s investigation; she also did not respond to more recent questions about whether the command would turn over information on the strike to members of Congress.

“The United States has a duty to provide clear information on the extent of support provided to the Nigerian military for the Rann airstrike and the consequences of this support,” said Anietie Ewang, Human Rights Watch’s Nigeria researcher. “If their collaboration with the Nigerian authorities in any way contributed to the killing of civilians during the strike, they should acknowledge this and share in the responsibility to ensure accountability and redress for victims, which the Nigerian authorities have failed to do.”

Secret U.S. involvement in other nations’ errant airstrikes is an underreported form of civilian harm. Earlier this year, The Intercept revealed how U.S. targeting assessments carried out for the Dutch military led to a 2015 airstrike on an ISIS bomb factory in Hawija, Iraq, that touched off secondary explosions, killing at least 85 civilians. No Americans were held accountable for the civilian deaths in the Hawija strike, in keeping with a litany of attacks from Somalia to Libya and from Syria to Yemen that the Pentagon has failed to investigate or reinvestigate despite civilian casualty allegations. The U.S. has conducted more than 91,000 airstrikes across seven major conflict zones and killed as many as 48,308 civilians, according to a 2021 analysis by Airwars, a U.K.-based airstrike monitoring group.

The Civilian Harm Mitigation and Response Action Plan — written at the direction of Austin in response to reporting by the New York Times and others — provides a blueprint for improving how the Pentagon addresses civilian casualties. The plan requires military personnel to consider potential harm to civilians in any airstrike, ground raid, or other type of combat. It also signals a more nuanced understanding of how civilian harm extends beyond deaths and injuries to include damage to infrastructure and essential services on which civilians depend, but experts say the plan is light on the question of accountability. That, potentially, is where Congress can play a key role.

“The Protection of Civilians in Conflict Caucus can make a mark with how they proceed on this case by ensuring they leave no stone unturned,” said Ewang. “They should go beyond uncovering the extent of U.S. involvement in the airstrike to asking critical questions about civilian casualty assessments and push for accountability and redress if there is any indication of U.S. responsibility.”