Syrian civil war is in its third year. The United Nations estimates that more than 70,000 people have died as a result of the war and at least 1 million people are displaced by conflict.
The U.N. Security Council has been sidelined by veto threats from Syrian allies like Russia, who say draft resolutions lack balance. The Turkish government has Patriot missiles deployed along the border to protect against spill over, though NATO forces said there's no intention of imposing a no-fly zone over Syria.
NATO intervened with a no-fly zone in Libya in 2011 to protect civilians from attacks from pro-government forces. Former U.N. humanitarian chief John Holmes told the BBC the answer wasn't that simple in Syria.
"From a humanitarian point of view, no fly-zones and humanitarian corridors pose enormous challenges," he said.
There are some levels of humanitarian assistance in parts of Syria under rebel control. Holmes said that calling for official humanitarian corridors meant the international community had to ensure security exists in a place where it can't be guaranteed.
The United Nations' World Food Program said there have been more than 20 attacks on its delivery vehicles and warehouses in Syria since it started working in the country in December 2011.