The United States has warned that it would respond appropriately to any chemical weapons attack by the regime of Bashar Assad, as members of the United Nations Security Council exchanged counter accusations on the deteriorating humanitarian situation in Syria and the threat to the lives of millions of civilians in Idlib province. US Representative to the UN Economic and Social Council Kelley Currie expressed concern to the Council that the Assad regime could once again use chemical weapons against its people, warning that “the United States, France and the United Kingdom are committed to responding appropriately to any such attacks.” The use of chemical weapons against civilian populations as part of the assault on Idlib would have “devastating consequences for humanitarian conditions on the ground” and would further erode the international regime prohibiting the use of chemical weapons, Currie said. She spoke after John Ging, Director of Operations and Advocacy for the UN Office for the Coordination of Humanitarian Affairs, told the Council that recent weeks have seen a further serious deterioration of the humanitarian situation in northwest Syria. Noting that aid partners are finalizing a comprehensive readiness plan for the northwest, he nevertheless said some 2.1 million people remain in need in areas under the control of armed groups. Emergency Relief Coordinator Mark Lowcock is in Damascus “to engage with the government on how best to scale up the collective humanitarian response,” he said. But Russias envoy, Ambassador Vassily Nebenzia, said the US has illegally created an airbase in southern Syria close to a refugee camp.  “To make a show of being humane to an audience is not necessary,” he insisted. “What is necessary is concrete assistance.” "We need to decouple moderate groups from terrorist groups" in Idlib, he said. He again accused Hayat Tahrir al-Sham of preparing a chemical attack, which Moscow says the West will use to justify a strike against Syrian forces. Russia also claims British special forces are helping the militants, including by possibly supplying chlorine, allegations vehemently denied by Britains Ambassador Karen Pierce who called them "baseless" and "outlandish." The heated exchange of accusations came after the Security Council held closed-door talks in which the Russian ambassador made further accusations on the possibility of the Syrian opposition’s use of chemical weapons. But a diplomat who attended the session said Nebenzia provided no evidence.