Frustrated with the ceasefire collapse in Syria, and with intensified fighting in the northern city of Aleppo, the UN Security Council convened an emergency meeting on Sunday. But it remains deadlocked over how to proceed.

As eastern Aleppo came under heavy bombardment in what may be one of the worst weeks in the Syrian conflict, the UN's Syria envoy delivered an impassioned plea to the Security Council to resume the cessation of hostilities, or C-O-H.

"please, develop a common course of action to enforce a cessation of hostilities in Syria. I am still convinced that we can turn the course of events," said Staffan de Mistura, UN Syria Envoy.

"We have proven this more than once before. We have come a long way to date to not allow the small but tangible achievements of the CoH to be buried under the dust of Aleppo's rubble."

The cessation of hostilities brokered by the US and Russia went into effect on September 12th and then collapsed a week later after the destruction of a UN aid convoy.

Washington blames Russia and the Syrian government for that attack, and Moscow blames the U.S. and opposition rebels.

The U.S. and its western allies want Russia and Syrian forces to stop targeting rebel groups. Russia says there's a difference between opposition rebels and terrorists.

"We don't have to order someone to do anything unilaterally, but we need to see we're talking about a sincere desire to separate those people who are working with the American coalition from Jabhat al-Nusra," said Vitaly Churkin, Russian Ambassador to the UN.

"Russia would have this council live in 'upside-down land' where bombing first responders, cutting off humanitarian aid, and supporting a murderous regime is billed as counterterrorism. What Russia is doing is not counter-terrorism. It's barbarism," said Samantha Power, US Ambassador to the UN.

As accusations continued to fly, China tried to steer the meeting back to a key area of concern.

"Counter-terrorism is a very important component to the Syrian conflict. Without rooting out terrorism there will be no peace for Syrians and no security for regional countries," said Liu Jieyi,Chinese Ambassador to the UN.

Intensified aerial bombing of heavily urbanized areas have left 275 thousand Syrians in eastern Aleppo without enough fuel, food and water, and strikes against first responders means the injured have less chance of survival.