WASHINGTON — Russia vetoed a measure on Friday that would have allowed the last U.N. aid route into Syria to remain open for another year, in a vote that diplomats and critics said endangered the lives of millions of people already suffering after more than a decade of war.
Foreign officials and international aid workers had implored Russia to approve a one-year extension for the humanitarian corridor, which leads from the Bab al-Hawa crossing at the Turkish border into northwest Syria. The U.N. mission, which started in 2014, expires on Sunday.
But with its veto on Friday, Moscow maintained its long-held insistence that the route violated Syrian sovereignty — and that it should be up to President Bashar al-Assad of Syria to decide how foreign support is distributed.
Thirteen members of the U.N. Security Council voted to continue the aid mission, and China abstained. Only Russia opposed it.
“This was a life or death vote for the Syrian people, and Russia chose the latter,” Linda Thomas-Greenfield, the U.S. ambassador to the United Nations, said after the vote. “This was already the bare minimum the Syrian people needed to survive.”
She and other diplomats said they would try to find another way to ensure that Syrians continue to receive food, medicine and other aid.
Russia had offered an alternate plan that would have kept the route open for six months and then given control over humanitarian assistance to Syria to Mr. al-Assad’s government.
But that proposal failed over concerns that the brief reprieve would create too much uncertainty among donors and relief groups, leading to a shortfall of supplies, and that the route would be shut down during the winter when the aid is needed most.
Russia’s deputy U.N. ambassador, Dmitry Polyanskiy, said that the one-year extension “ignored the interests” of Syria and that the six-month respite would have staved off “the ultimate closure of the crossing.”
“Our position has been clear on the issues here and have been known to everybody from the very beginning,” Mr. Polyanskiy said. “We haven’t misled anyone.”
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He urged diplomats to support the Russian plan, “if, of course, the fate of the project is important, and not your dubious political games.”
More than 5.7 million Syrians have fled the country since civil war began in 2011. The border crossing’s closure could force thousands more to leave, setting off another refugee crisis in countries in the Middle East and Europe that are already dealing with an influx of people escaping conflicts in Afghanistan, Ukraine and sub-Saharan Africa.
It was also one of the few areas of compromise between the United States and Russia, which had for years negotiated agreements to leave the route open but ended nearly all diplomatic communications after Moscow invaded Ukraine in February.
U.N. officials have described the Bab al-Hawa route as the gateway for the world’s largest humanitarian aid operation, one that has delivered more than 56,000 truckloads of lifesaving supplies to Idlib Province in northwestern Syria over the last eight years. As many as four million people in Syria — including an estimated 1.7 million who are living in tents — receive supplies that are delivered to Idlib.
Aid groups estimate that 70 percent of Syria’s population does not have reliable food supplies.
“Closing the cross-border could result in catastrophic consequences,” Dr. Khaula Sawah, the president of the U.S. chapter of the Union of Medical Care and Relief Organizations, said in a statement ahead of the U.N. vote.
Idlib is the last large rebel enclave in Syria and an area that has also become a haven for extremists linked to Al Qaeda. Russian diplomats have warned that aid delivered there was vulnerable to being taken by terrorist groups.
Russia is one of Mr. al-Assad’s benefactors in the war and used its veto power at the U.N. Security Council to help shut down three other humanitarian corridors into Syria in 2020. Russia agreed last year to keep Bab al-Hawa open after intense negotiations with the United States, with the understanding that the U.N. mission’s mandate would expire on July 10.
Top officials in Congress have accused Russia of helping Mr. al-Assad starve his political opponents by trying to control where the international assistance is distributed.
“We vehemently condemn the Russian government’s efforts to hinder the delivery of badly needed aid to the Syrian people, and to perpetuate the numerous atrocities being committed against the people of Syria by the Assad regime, Russia and Iran,” the Democratic and Republican leaders of the House and Senate committees that oversee American diplomacy said in a statement this week.
A vast majority of Syrian refugees live in Turkey, where officials have warned for years that the diaspora is pushing the country to a breaking point.
Current and former diplomats have said Russia had appeared to use the aid corridor as a bargaining chip in persuading Turkey to side with some of Moscow’s demands over the war in Ukraine. But late last month, President Recep Tayyip Erdogan of Turkey dropped his opposition to allowing Sweden and Finland into NATO, infuriating Moscow.
Speaking to reporters after Friday’s vote, Mr. Polyanskiy said Russia would “obviously” veto other proposals to keep the route open if they deviated from the six-month plan he had offered.
Other diplomats noted that efforts were being made to broker a nine-month extension, but Ms. Thomas-Greenfield said it was unclear that an agreement could be reached before Sunday’s deadline.
China’s ambassador to the United Nations, Zhang Jun, said negotiations could continue even after Sunday, given “the humanitarian situation in Syria and caring for the suffering of the Syrian people.”
“We still have some time,” Mr. Zhang said, calling on diplomats “not to give up.”