On December 12, 2013, a U.S. drone attack on a wedding convoy outside the Yemeni city of Rad’a killed 12 men and wounded at least 15 other people, including the bride. U.S. and Yemeni officials, speaking on condition of anonymity, have said those killed were members of Al-Qaeda in the Arabian Peninsula. But statements by relatives and witnesses, and the actions of provincial authorities in the strike area, suggest that some if not all of those killed were civilians.

The likelihood of civilian casualties in this strike, which I researched last month in Yemen for Human Rights Watch, raises the prospect that the U.S. violated the laws of war, either by failing to discriminate between combatants and civilians, or by causing disproportionate civilian loss compared to the attack’s military gain.  Civilian casualties also beg the question of whether the attack violated President Obama’s policy on targeted killings, announced last May, of “near-certainty” that no civilians will be harmed in airstrikes on terrorism suspects beyond conventional battlefields.

These are serious allegations that demand official responses from the Obama administration, which has promised greater transparency on targeted killings. But rather than provide an official accounting, the U.S. has fallen back on its usual pattern of near-silence and obfuscation on drone strikes, suggesting a chilling indifference to addressing potential civilian harm. The few crumbs of information are doled out by government sources whose comments often raise more questions than they answer.

For example, U.S. government sources on Feb.20 told the Associated Press that both the Pentagon and the White House investigated the strike on the wedding convoy and concluded that “no civilians were killed.” To support their assertions, the sources said they watched a video of the strike showing that three vehicles in the convoy were hit, “all carrying armed men.”

But most men carry assault rifles in rural areas of Yemen, the world’s most heavily armed country after the U.S., and gunshots are customary at wedding celebrations. The video may shed more light on the men targeted, but the U.S. has refused to release it, just as it refuses to release any of the videos it has of every one of its drone attacks.

The Washington Post also reported that the Pentagon investigated the strike. It quoted unnamed U.S. government sources who said the inquiry “supports the U.S. contention that the targets were al-Qaeda militants,” but who “declined to elaborate.” Their comment leaves unanswered the question of whether the men the U.S. had targeted were the ones the strike ended up killing. One reason this distinction is important is that U.S. government sources earlier told media and Human Rights Watch that the main target of the strike—an Al-Qaeda in the Arabian Peninsula member allegedly involved in plots against U.S. embassies—was wounded but escaped.

National Security Council spokeswoman Caitlin Hayden, meanwhile, has referred media and Human Rights Watch to a Yemeni government statement about the attack, even though no one disputes that the U.S., not Yemen, carried it out. That statement—in Arabic—calls the targets “dangerous senior al-Qaeda militants” involved in operations against Yemen, but includes no information that they posed a threat to the U.S. or any details that would support the attack’s legality.

The unnamed sources who spoke to the Associated Press said the U.S. cannot officially comment because strikes in Yemen are carried out by both the CIA, whose operations are covert, and the U.S. military. “[I]f they explain one strike but not another,” the officials told the Associated Press, “they are revealing by default which ones are being carried out by the CIA.”  

The expressed need for CIA deniability has long been a feature of the U.S. drone program, used to justify a “no comment” response to strikes not only in Yemen but also in Pakistan and Somalia. But domestic statutory requirements regarding the CIA do not absolve the U.S. of its international legal obligations to both investigate potentially unlawful attacks and provide redress for wrongdoing. Beyond the serious legal implications, U.S. silence on possible civilian casualties fuels public distrust in Yemen and other targeted locales.

The obvious way out of this information blackout is for Obama to stop dithering on his pledge to transfer all drone attacks from the CIA to the Pentagon—and for Congress to stop throwing obstacles in his way. The administration should also allow rigorous public scrutiny of operations by the Joint Special Operations Command, the elite, quasi-covert agency that carries out drone strikes within the Pentagon.

In the meantime, the U.S. needs to officially clarify some basic facts about the December 12 strike. All Yemenis, especially the families of the dead and wounded, deserve to know why this wedding procession became a funeral.

Tayler is a senior terrorism and counterterrorism researcher at Human Rights Watch and the author of two recent reports on U.S. targeted killings in Yemen, including “A Wedding That Became a Funeral: U.S. Drone Attack on Marriage Procession in Yemen.”