The House on Thursday narrowly defeated a measure that would have banned the transfer of cluster bombs to Saudi Arabia, but the closeness of the vote was an indication of growing congressional opposition to the conduct of the U.S.-backed, Saudi-led bombing coalition in Yemen.

The vote was mostly along party lines, with 200 Republicans – and only 16 Democrats – heeding the Obama administration’s urging to vote against the measure. The vote was 204-216.

“The Department of Defense strongly opposes this amendment,” said Rep. Rodney Frelinghuysen, R-N.J., chairman of the House Committee on Defense Appropriations, during floor debate. “They advise us that it would stigmatize cluster munitions, which are legitimate weapons with clear military utility.”

Cluster munitions are large shell casings that scatter hundreds or thousands of miniature explosives over large areas – often the size of several football fields. Some of the bomblets fail to explode on impact, leaving mine-like explosives that kill civilians and destroy farmland decades after a conflict ends.

Cluster bombs are banned by an international treaty signed by 119 countries, not including the United States. The United States opposed the treaty, and instead of signing it, adopted a policy that cluster bombs should never be used in concentrated, civilian areas.

Speaking in support of the amendment, Rep. Hank Johnson, D-Ga., said Saudi Arabia has deliberately targeted civilians with cluster bombs. “Earlier this year, the Saudi-led coalition dropped cluster bombs in Yemen’s capital of Sanaa, specifically targeting known civilian neighborhoods,” he said. “One of the buildings hit was the al Noor Center for Care and Rehabilitation for the Blind, which also has a school for blind children. The destruction of the school and the injuries sustained by the children was unbearably gruesome.”

The coalition has also used U.S.-produced weapons to destroy markets, factories, and hospitals.

The vote came the day after one of the war’s key architects, Mohammed Bin Salman, the Saudi deputy crown prince and defense minister, met with lawmakers to discuss, among other things, “the threat posed by Iranian aggression in … Yemen, and the broader Middle East.”

Despite the defeat, human rights activists celebrated the closeness of the vote. “This is a big deal for the U.S.-Saudi Arabia alliance,” said Sunjeev Bery, Amnesty International’s advocacy director for the Middle East in the U.S. “More and more members of Congress are clearly getting tired of selling Saudi Arabia bombs when it is dropping them on civilians in Yemen.”

The vote comes at a time when the U.S.-Saudi alliance is facing unprecedented skepticism in the United States. Although the Obama administration has refused to publicly condemn the use of cluster bombs, Foreign Policy reported that the White House has quietly placed a hold on a transfer of CBU-105 cluster bombs. A bipartisan group of lawmakers is trying to place a complete arms embargo on the kingdom, until it stops deliberately targeting civilians in Yemen.

The Saudis faced further loss of support Thursday when Sheikh Mohammed bin Zayed Al Nahyan, the deputy crown prince of the UAE, announced on Twitter that the “war is over” for Emirati troops. The UAE had previously been one of the most active members of the coalition.