The Pentagon more than doubled US refueling support for the Saudi-led mission in Yemen over the past year, a spokeswoman told Al-Monitor, despite mounting public and congressional concerns about the operation.

Amid a worsening humanitarian crisis in the war-torn country, the US Department of Defense provided about 480,000 gallons of aviation fuel to the mission at a cost of more than $1 million in the fiscal year that ended Sept. 30, a 140% increase over the previous year. The disclosure comes as Yemen suffers the world’s worst cholera epidemic and the Saudis face international pressure to lift their blockade of the country’s ports.

“This revelation should be a wake-up call to every policymaker and every American that this country is literally fueling the largest humanitarian crisis in the world and the worst cholera outbreak in recorded history,” said Kate Gould, a lobbyist with the Friends Committee on National Legislation, a Quaker group. “The [United States] is operating these gas stations in the sky to fuel Saudi and UAE bombers as they rain down terror on Yemeni water and other sanitation infrastructure — the last safeguards Yemen has against these disease outbreaks sweeping the country.”

Though top Pentagon officials say that the United States no longer assists the Saudi-led coalition with targeting Iran-backed Houthi rebels in Yemen, the refueling mission has continued to expand under President Donald Trump. The Pentagon buys its fuel from the Defense Logistics Agency, an in-house organization that provides supplies to the US military and then sells it to individual military services, including the US Air Force, which is spearheading the refueling mission. The United States has conducted 2,363 refueling sorties in the Horn of Africa since the Saudi-led campaign began in March 2015, but US Central Command, which tracks that data, does not break out figures by country.