A key United Nations official on Thursday called for a 48-hour cease-fire in war-torn Aleppo in order to let humanitarian groups bring food and medicine into the Syrian city, and Russia signaled that it’s ready to support that idea.

UN envoy for Syria Staffan de Mistura said the cease-fire would be a “gesture of humanity from both sides” to help the two million people trapped in the divided city. De Mistura told reporters that he angrily left a meeting of the Humanitarian Task force after less than 10 minutes because not a single convoy had been allowed to reach and aide any of Aleppo’s besieged areas.