NEW YORK — US Secretary of State John Kerry and UN Syria envoy Staffan de Mistura emerged from a grim meeting of International Syria Support Group (ISSG) foreign ministers this morning declaring the Syrian cease-fire was not dead, a day after airstrikes by the Syrian regime or Russia killed 20 civilians and destroyed 18 trucks in a convoy of humanitarian aid being delivered to western Aleppo. US and international officials, however, are expressing growing doubts about whether the US-Russia agreement to try to stabilize Syria is viable, after struggling to make it take hold since it went into effect Sept. 12.

“The ceasefire is not dead. That I can tell you,” de Mistura said Tuesday after the ISSG morning meeting on the sidelines of the UN General Assembly meeting in New York. “It was confirmed by everyone around the table.”

“The ceasefire is in danger … but the only ones who can announce the ceasefire is dead are the two [US and Russian] co-chairs and they have today not done so,” de Mistura said. “They want to give it another chance.”

The ISSG foreign ministers “agreed that despite continued violence, there was still an imperative to pursue a nationwide cessation of hostilities based on the arrangement reached last week in Geneva between the United States and Russia,” State Department spokesman John Kirby said in a read-out Sept. 20. The group will meet later in the week to discuss next steps, he said.