US Secretary of State John Kerry has once more called for cooperation from Russia as he begins urgent talks in Geneva aimed at bolstering a fragile ceasefire in Syria. The Obama administration wants Moscow, a key ally of Syrian President Bashar al-Assad, to put pressure on the Syrian regime to stop the bombardment of the country’s second city. Responding to Kerry’s appeals, Russia said Sunday it was working to halt the fighting in Aleppo. The bloodshed in Aleppo has been at the centre of an escalation of violence that has all but destroyed a wider ceasefire deal brokered by Moscow and Washington on February 27.