The fate of the last cross-border humanitarian corridor through which life-saving aid to millions of Syrians is delivered hangs in the balance once again, with Russia threatening to wield its veto power at the UN Security Council to block it.

The United States has launched an all-out diplomatic effort to dissuade Russia from such action, emphasizing the likely horrific consequences if it were to go through with its threat.

Some 3 million Syrians displaced by the country’s decadelong conflict, sheltering in dire conditions in the northwest province of Idlib on the Turkish border, would be directly affected.

US Ambassador to the United Nations Linda Thomas-Greenfield, who toured the Turkish-Syrian border last week, told reporters, “This is their lifeline. Over the last year and a half, some members of the Security Council succeeded in shamefully closing two other crossings into Syria.” The envoy was referring to humanitarian corridors through Iraq that supplied the Kurdish-administered northeast of the country and Jordan. Both were shut down because of Russia’s and China’s objections, part of Moscow’s ongoing drive to force the international community to channel aid via Damascus and bolster the legitimacy of the Assad regime. Another, via Turkey Bab al-Salam, was also shut down in June 2020 due to Russia.