As the relationship between the United States and Saudi Arabia comes under renewed scrutiny in the wake of the Gulf nation’s weekend bombing campaign in Yemen, a Reuters exclusive published Monday reveals that the Obama administration approved a $1.3 billion arms sale to Saudi Arabia last year despite warnings that it could implicate the U.S. in war crimes.

The Saudi-led airstrikes in Yemen on Saturday killed at least 140 people and wounded hundreds more, prompting the U.S. to launch a “review” of its support for the kingdom. On Monday, Reuters reported that the U.S. Department of State had already warned the government that “the United States could be implicated in war crimes” for aiding the campaign.

Officials also had doubts that the Saudi military would actually be able to target Houthi militants without hurting civilians or destroying infrastructure, according to department emails and interviews with officials.

However, government lawyers stopped just short of concluding that U.S. support for the campaign would implicate the country in war crimes—which could have opened up the U.S. military to accountability. Reuters writes:

U.S. government lawyers ultimately did not reach a conclusion on whether U.S. support for the campaign would make the United States a “co-belligerent” in the war under international law, four current and former officials said. That finding would have obligated Washington to investigate allegations of war crimes in Yemen and would have raised a legal risk that U.S. military personnel could be subject to prosecution, at least in theory.

The documents, obtained by Reuters through a Freedom of Information Act (FOIA) request, shed new light on “how the United States pressed the Saudis to limit civilian damage and provided detailed lists of sites to avoid bombing, even as officials worried about whether the Saudi military had the capacity to do so,” Rueters continues.

American officials were actually well aware that airstrikes in Yemen were killing scores of civilians. Reuters writes:

State Department lawyers “had their hair on fire” as reports of civilian casualties in Yemen multiplied in 2015, and prominent human rights groups charged that Washington could be complicit in war crimes, one U.S. official said. That official and the others requested anonymity. During an October 2015 meeting with private human rights groups, a State Department specialist on protecting civilians in conflict acknowledged Saudi strikes were going awry. “The strikes are not intentionally indiscriminate but rather result from a lack of Saudi experience with dropping munitions and firing missiles,” the specialist said, according to a department account of the meeting.

The specialist also noted that “weak intelligence” had contributed to confusion over who was who on the ground.

The investigation comes just after the U.S. approved yet another billion-dollar arms sale to Saudi Arabia. At the time of the authorization in September, Oxfam America president Ray Offenheiser condemned the deal as continued evidence of both nations’ “startling indifference to civilian lives.”

Indeed, as Common Dreams reported over the weekend, the Obama administration’s new review has little credibility among anti-war advocates. Although National Security Council spokesman Ned Price rebuked the airstrikes Saturday night, stating, “U.S. security cooperation with Saudi Arabia is not a blank check,” United Nations-based journalist Samuel Oakford pointed out in response that the government has long been making that empty declaration.

“WH used this ‘not a black check’ language for months,” he tweeted, noting that there is also no deadline for the review and that “refueling continues.”