FOR WEEKS after a clash between the Ni­ger­ian army and Islamic militants last month in the remote fishing village of Baga, it was difficult for outsiders to determine what had happened. Residents who fled to the state capital told the New York Times and human rights organizations that at least 180 people had been killed when the army went on a rampage, burning much of the village of thatch-roofed homes and shooting residents as they tried to flee. Ni­ger­ian officials claimed that only a handful of civilians had died and only 30 homes were destroyed; they said the fires started when militants fired rocket-propelled grenades and set off homemade bombs.

Satellite imagery commissioned by Human Rights Watch has now made clear that a serious atrocity occurred. The organization reported last week that it had counted 2,275 destroyed buildings in the images. It said the razing was intentional, corroborating the accounts of residents who said the army torched the village after a soldier was killed in a clash with the Boko Haram militant group.

There are several reasons why this incident should be taken seriously by the Obama administration and other governments. First, while the incident may have been exceptional in scope, such abuses are not uncommon: In fighting Boko Haram, a terrorist group that has committed many atrocities of its own, the Ni­ger­ian army has repeatedly killed innocent civilians. A Human Rights Watch reportin October documented how the military task force fighting Boko Haram in its northern Nigeria strongholds had engaged in secret detentions, extortion, burning of homes and extrajudicial killings. These have generated sympathy and fresh recruits for the militants and helped raise the death toll in the conflict to more than 3,000 since 2009.

Such abuses should matter in Washington because the United States is providing assistance to the Ni­ger­ian army, including training and help with communications and transport. Such aid makes sense: Boko Haram, which is believed to have ties to al-Qaeda, is a serious threat. However, under U.S. law, aid cannot be provided to forces that are known to have committed human rights abuses; more broadly, the United States has a strong interest in preventing practices that themselves foster extremism.

Perhaps most important, the Baga incident matters because it has prompted an unusual outcry in Nigeria itself. Members of the National Assembly have called for an investigation and President Goodluck Jonathan has appeared to acknowledge the need for one. By insisting on accountability in this case, the United States and other outside actors may be able to have an effect on the military’s heavy-handed tactics.

The State Department appears to recognize the opportunity. Last week a spokesman condemned“the loss of life and mass destruction of dwellings in Baga,” and urged a “full investigation” to hold accountable “those responsible, both military and others.” A senior U.S. human rights official was due in Nigeria’s capital, Abuja, this week to discuss Baga “and broader human rights issues,” the spokesman said.

That’s a start. But the administration should not let the matter drop if Ni­ger­ian authorities are slow to pursue an investigation. It should be made clear to Nigeria’s generals that continued military cooperation with Washington depends on acknowledging the problems with the campaign against Boko Haram and undertaking reforms.