UN: Number of Syrians Under Siege Doubled in 6 Months, Now Nearly 1 Million U.N. figures point to the Syrian government and Islamic State as main culprits.

 -- The number of Syrians living under siege has doubled in just the past six months and now totals nearly one million, the United Nations' humanitarian chief said on Monday.

Stephen O'Brien, the U.N.'s Under-Secretary-General for Humanitarian Affairs, told the United Nations Security Council that the number of Syrians under siege increased from 486,700 six months ago to 974,080 today.

"Civilians are being isolated, starved, bombed and denied medical attention and humanitarian assistance in order to force them to submit or flee," O'Brien said of the situation.

"Horror is now usual – it is a level of violence and destruction that the world appears to consider normal for Syria and normal for the Syrian people."

Calling it a deliberate tactic of cruelty, O'Brien said that many Syrian civilians are faced with the choice of either “starve, get bombed or surrender.”

The Syrian government is responsible for 850,000 of the nearly one million besieged Syrians, U.N. figures estimate, with the Islamic State and other warring groups making up the remainder.

About 275,000 people remain trapped in rebel-held areas of Aleppo, where Syrian government airstrikes in the past week have killed dozens and knocked out medical facilities.

Outside of Aleppo, more than 400,000 people are encircled by conflict around the capital of Damascus.