If there were an Olympics for waging bloody wars, Saudi Arabia and its Arab coalition allies would surely win a medal for their relentless bombing of Yemen over the past year and a half to crush rebels who seized power in 2014.

One international NGO has called the ongoing war in Yemen “arguably the worst humanitarian crisis in the world,” which is saying a lot considering the competition from Syria, Iraq, Libya and Afghanistan.

When I first wrote about the Yemen conflict in April 2015, the death toll stood at several hundred, with more than a quarter million people displaced. Today the United Nation’s human rights office estimates that more than 10,000 people have been killed and three million displaced. The World Food Programme reports that seven million people — more than a quarter of Yemen’s population — are “on the brink of famine.”

In March, the U.N. human rights chief accused the Saudi-led coalition of causing “twice as many civilian casualties as all other forces put together, virtually all as a result of air strikes.” Given the regularity of bombing attacks on hospitals, clinics, schools, wedding parties and other civilian targets, he added, “we are possibly looking at the commission of international crimes by members of the coalition.”

The war is destroying Yemen’s cultural heritage as well. Last fall when the director of Yemen’s General Organization of Antiquities and Museums reported that Saudi-led bombing raids in his country had destroyed six ancient cities, six castles, three museums, two mosques, four palaces, and other priceless archeological sites throughout the country — including much of the ancient city of Sana’a, a UNESCO World Heritage site.

Earlier this year the U.N. pulled back from condemning Saudi Arabia after the kingdom threatened to yank hundreds of millions of dollars from international programs. Private human rights organizations, on the other hand, have not hesitated to accuse the coalition of committing war crimes.

This week, Middle East Eye reported that “The humanitarian calamity in Yemen entered a terrifying new phase of horror” as Saudi Arabia resumed air strikes on the capital city of Sana’a following the failure of peace talks in Kuwait: “The assaults are destroying civilian infrastructure, and threaten to prevent food and desperately needed aid from reaching the capital.”

On Aug. 20, Saudi pilots bombed downtown Sana’a as hundreds of thousands of people gathered in the largest demonstration in the country’s history to protest the war. Other recent bombing raids have killed dozens of civilians at sites including a potato chip factory, a school, the main bridge used to transport food to the capital, and a medical center run by Doctors Without Borders. The latter attack — the fourth targeting its facilities in the past year — prompted the organization to evacuate all of its medical teams from north Yemen.

Pushing Back on Washington’s Support

In return for Riyadh’s agreement not to oppose the nuclear deal with Iran, Washington has backed Saudi Arabia’s bloody intervention with diplomatic support in the United Nations, military intelligence and aircraft refueling assistance, and an open-ended weapons pipeline. U.S. arms sales to Saudi Arabia during the Obama years have amounted to $48 billion, three times the total under George W. Bush.

In June, Secretary of State John Kerry dismissed international concerns about the carnage, telling an interviewer, “I think the Saudis have expressed in the last weeks their desire to make certain that they’re acting responsibly, and not endangering civilians.”

But the Obama administration’s support for Saudi Arabia’s criminal policies is at last beginning to trouble many legislators on Capitol Hill.

On Aug. 29, 64 members of Congress asked President Obama to postpone his latest plans to sell $1.2 billion of weapons to Saudi Arabia, including tanks and machine guns for use in Yemen. Their letter declares that documented attacks by the Saudi-led coalition in Yemen against hospitals, schools, markets, and places of worship “may amount to war crimes.”

The bipartisan letter, co-led by Reps. John Conyers, D-Michigan, Ted Lieu, D-California, Mick Mulvaney, R-South Carolina, and Ted Yoho, R-Florida, takes Obama to task for notifying Congress of the latest planned arms sale on Aug. 8, during the usual congressional recess, giving legislators little time to consider the deal after they return within the 30-day review window established by law.

The letter also chides Obama for ignoring a vote last June by 204 members of the House, including 40 Republicans and all but 16 Democrats, “to block the sale of cluster bombs to Saudi Arabia after reports of their use in civilian areas in Yemen.” (More than 108 nations, not including the United States, have signed the Convention on Cluster Munitions, pledging never to use or transfer such vicious weapons, which are notorious for killing and maiming civilians.)

Rep. Lieu, who represents Los Angeles County, said in a statement accompanying the letter, “The actions of the Saudi-led coalition in Yemen are as reprehensible as they are illegal. . . . Hospitals, schools, and wedding parties are not legitimate military targets. Saudi Arabia is either intentionally targeting civilians or deliberately indifferent in executing its military operations – either case flies in the face of long-standing international standards of conduct.

“The United States of America should never support such atrocities in any way. They are not only immoral and unlawful, but they seriously harm our national security and moral standing around the world.”

The letter was endorsed by a host of NGOs, including Amnesty International USA, Human Rights Watch, Oxfam, Physicians for Human Rights, and the traditionally conservative Hudson Institute.

Hope for Challenging the Saudis

Robert Naiman, whose organization Just Foreign Policy also supported the congressional letter, told me “this is the first time we’ve had so many members of Congress signing such a letter and getting significant attention” for the Yemen war.

He added, “If there is enough discord, the administration may back off. This will put pressure on them to get a renewal of the ceasefire and the political process in Yemen.”

As evidence that human rights campaigns and congressional complaints can make a difference, Naiman cited the breaking news that Textron Systems, the last remaining U.S. manufacturer of the cluster bombs dropped by Saudi Arabia in Yemen, is ending production of the munitions. Explaining its decision, Textron said “The current political environment has made it difficult to obtain” approvals from Congress and the administration.

When Congress returns to session on Sept. 6, Senators Chris Murphy, D-Connecticut, and Rand Paul, R-Kentucky, plan to introduce a resolution in their chamber to disapprove the pending arms sale.

Sen. Murphy told CNN on Aug. 16, after Saudi Arabia bombed a hospital run by Doctors Without Borders, “There’s an American imprint on every civilian life lost in Yemen. Why? Well it’s because although the Saudis are actually dropping the bombs from their planes, they couldn’t do it without the United States.”

The chances are small that the Republican-led Senate will turn down further arms sales to Saudi Arabia, but a recent close Senate committee vote on training funds for Saudi Arabia suggests that opposition is growing in that branch as well.

“The dynamic has changed,” says Naiman, crediting antiwar activists in Congress and private organizations. “Criticism of Saudi Arabia is not taboo anymore. We have changed perceptions, and we are on the playing field in a way we never were before.”