This picture taken on Jan. 31, 2014, and released by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA), shows residents of the Palestinian camp of Yarmouk queuing to receive food supplies in Damascus, Syria. A UN official is calling on warring sides in Syria to allow aid workers to resume distribution of food and medicine in a besieged Palestinian district of Damascus. The call comes as U.N. Secretary General Ban Ki-Moon urged Syrian government to authorize more humanitarian staff to work inside the country, devastated by its 3-year-old conflict.
Smoke rises from buildings after what activists said was shelling from forces loyal to Syria's President Bashar al-Assad in the besieged area of Homs, Syria on Jan. 15, 2014.
Thaer Al Khalidiya/Reuters
Residents carry an injured man that survived shelling after what activists said was an air strike from forces loyal to Syria's President Bashar al-Assad in Takeek Al-Bab area of Aleppo on December 17, 2013.
A young Syrian refugee carries a blanket next to a tent in a makeshift refugee camp in the Lebanese village of Qaraoun in the Bekaa Valley, on December 12, 2013.
Mahmoud Zayyat/AFP/Getty Images
Syrian refugee women stand in line to receive their families share of winter aid kits at Zaatari refugee camp, near the Syrian border, in Mafraq, Jordan, Dec. 3, 2013.
Residents run from a fire at a gasoline and oil shop in Aleppo's Bustan Al-Qasr neighborhood, Oct. 20, 2013, in Syria. Witnesses said it was caused by a bullet fired by a sniper loyal to Syrian President Bashar al-Assad at the Karaj al-Hajez crossing, a passageway separating Aleppo's Bustan al-Qasr, which is under rebel control, and the Al-Masharqa neighborhood, an area controlled by the regime.
In this Oct. 03, 2013 photo, sons of Mohammed Kale rebuild a house wall damaged by a mortar shell that landed days before at their family house in Kfar Lata, a ghost village at the top of a mountain subdued under heavy shelling and bombardments due the fighting between opposition fighters and government forces in the Idlib province countryside of Syria.
A member of the 'Ansar Dimachk' Brigade, part of the 'Asood Allah' Brigade which operates under the Free Syrian Army, uses an iPad during preparations to fire a homemade mortar at one of the battlefronts in Jobar, Damascus, Syria on September 15, 2013.
Rebel fighters duck as they run behind a barricade to avoid being fired at by Syrian regime forces in the Old City's front line in Aleppo on September 18, 2013.
JM Lopez/AFP/Getty Images
A man mourning over one among many dead bodies after an alleged poisonous gas attack fired by regime forces, according to activists, in Douma City, Damascus, Syria, Aug. 21, 2013.
Media Office Of Douma City/AP Photo
This Aug. 21, 2013, file image provided by by Shaam News Network, which has been authenticated based on its contents and other AP reporting, purports to show several bodies being buried during a funeral in a suburb of Damascus, Syria.
Syrian refugees cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013.
Syrian refugees cross the border into the autonomous Kurdish region of northern Iraq, Aug. 17, 2013. Faced with brutal violence and soaring prices, thousands of Syrian Kurds have poured into Iraq's autonomous Kurdish region, seeking respite from fighting between Kurdish fighters and jihadists.
Safin Hamed/AFP/Getty Images
A Syrian youth dives into a swimming pool as people enjoy a day out in the northern city of Aleppo, July 12, 2013.
JM Lopez/AFP/Getty Images
A Syrian girl crosses the street holding a bag in the centre of Syria's northeastern city of Deir Ezzor, June 28, 2013.
Abo Shuja/AFP/Getty Images
A Free Syrian Army fighter feeds a cat bread in the old city of Aleppo, Syria on Jan. 6, 2013.
Andoni Lubaki/AP Photo
Dark clouds hang over buildings in Aleppo, Syria, Dec. 4, 2012.
Narciso Contreras/AP Photo
A father cries while holding his dead child in front of Dar al Shifa Hospital in Aleppo, Syria, Oct. 4, 2012. The Syrian Army has continued to shell Aleppo and claims Al-Sakhour district is now clear of mercenaries and terrorists.
Syria youths react following an airstrike by Syrian government forces in Maaret al-Numaan Oct. 18, 2012.
Bulent Kilic/AFP/Getty Images
A masked opposition fighter poses inside the Shaar district police station in the northern Syrian city of Aleppo after it was overrun by Free Syrian Army forces on July 25, 2012.
Pierre Torres/AFP/Getty Images
Syrian rebel fighter, Tawfiq Hassan, 23, a former butcher, poses for a picture, after returning from fighting against Syrian army forces in Aleppo, at a rebel headquarters in Marea on the outskirts of Aleppo city, Syria, Aug. 26, 2012.
Muhammed Muheisen/AP Photo
Syrians shout slogans during an anti-government demonstration after Friday prayers in the city of Binnish in Idlib province on June 29, 2012.
Cars burn at the scene of two suicide bombs in al-Qazar residential area in Damascus, Syria, May 10, 2012.
Syrian soldeirs celebrate in the al-Midan area in Damascus on July 20, 2012, Syria.
Louai Beshara/AFP/Getty Images
Ahmed, center, mourns his father, Abdulaziz Abu Ahmed Khrer, who was killed by a Syrian Army sniper, during his funeral in Idlib, north Syria, March 8, 2012.
Rodrigo Abd/AP Photo
Syrian mourners, one carrying the pre-Baath national flag adopted by the rebel movement, carry the body of a youth reportedly killed in violence in the northwestern Idlib region before his burial, Feb. 23, 2012. Three Syrian soldiers were killed and seven others wounded in a bomb at the southern entrance to the flashpoint city of Idlib , according to SANA news agency.
Bulent Kilic/AFP/Getty Images
Syrian rebels gather in front of the remains of a burnt military vehicle belonging to Syrian government forces destroyed by the rebels during clashes at Khaldiyeh neighborhood in Homs province, Syria on Feb. 23, 2012.
Demonstrators hold portraits of Syrian President Bashar al-Assad, in front of the Syrian embassy in Sofia, in this April 17, 2011 file photo.
Nikolay Doychinov/AFP/Getty Images
Syrians hold up a giant Syrian flag during a pro-regime demonstration in the western residential Damascus suburb of Mezze, June 15, 2011, as embattled President Bashar al-Assad came under intense world pressure to halt a crackdown on democracy protests.