Moscow on Tuesday blasted criticism by Washington over its actions in Syria, saying it was "unacceptable" to demand restraint around Aleppo, the city divided between Syrian government troops and rebels. "As soon as there is real headway in fighting terrorists, made by the Syrian government and army with our support, the Americans started... demanding that we stop fighting terrorists," Deputy Foreign Minister Sergei Ryabkov told RIA-Novosti agency. Britain-based monitors reported that Russia launched heavy air strikes in the Aleppo outskirts, slowing a last-ditch effort by rebels to break the siege.