In a sign of renewed tensions between the two powers, who back opposing sides in the conflict, key regime ally Moscow accused Washington of failing to meet its obligations under the truce deal it brokered with Moscow.
Russia’s ambassador to the United Nations, Vitaly Churkin, said Moscow wanted a UN Security Council resolution endorsing the deal.
“We are working on it,” he told reporters in New York, adding that he thought it should be adopted when the Security Council meets on Syria next Wednesday.
The UN said trucks loaded with aid were for a second day in a buffer zone between Turkey and Syria, voicing hope the supplies could be delivered to besieged rebel-held districts of Aleppo city on Friday.
The ceasefire deal calls for the demilitarisation of the key Castello Road into the city.
Russia said Thursday that Syrian armed forces were “fulfilling their obligations and have started a gradual withdrawal” from the route, but rebel groups did not appear to be carrying out a simultaneous pullback as agreed.