A man stands on a rooftop as he tries to find a signal for his cell phone in the besieged rebel bastion of Douma, northeast of the Syrian capital Damascus on October 26, 2014. #

Rebel fighters fire a cannon, locally known as the Hell Cannon, towards government positions on October 24, 2014, in Handarat, on the northern outskirts of the Syrian city of Aleppo. Syrian rebels fought fierce clashes with loyalist troops in the divided area of Handarat just north of Aleppo a day after fighting that killed 15 soldiers and pro-regime militia as well as 12 rebels, said the Syrian Observatory for Human Rights. #

Civilians inspect a site hit by what activists said was a missile fired by forces loyal to Syria's President Bashar al-Assad in al-Kalaseh neighborhood of Aleppo on October 28, 2014. #

The aircraft carrier USS George H.W. Bush transits the Gulf of Aden in this U.S. Navy handout picture taken October 23, 2014. The George H.W. Bush Carrier Strike Group is returning to Naval Station Norfolk after supporting maritime security operations, strike operations in Iraq and Syria. #

A collection of airstrikes on the Syrian city of Kobani by the US-led coalition, as seen from Suruc, at the Turkey-Syria border, throughout October and November of 2014. Kobani, also known as Ayn Arab, and its surrounding areas, has been under assault by extremists of the Islamic State group since mid-September and is being defended by Kurdish fighters and coalition airstrikes. (Left-to-right, top-row-to-bottom-row: AP Photo/Lefteris Pitarakis, Getty Images/Gokhan Sahin, AP Photo/Vadim Ghirda, Reuters/Kai Pfaffenbach, AP Photo/Lefteris Pitarakis, AP Photo/Vadim Ghirda, Reuters/Kai Pfaffenbach, AP Photo/Levend Ali, Reuters/Yannis Behrakis, AFP/Getty Images/Aris Messinis, AFP/Getty Images/Aris Messinis, Reuters/Osman Orsal) #

A fighter of the Kurdish People's Protection Units (YPG) uses a pair of binoculars as she looks towards areas controlled by Islamic State fighters in the southern countryside of Ras al-Ain on November 9, 2014. #

Mustafa's father (center) cries hearing his son suffering as he helps a doctor to stretch the boy's legs at a physical therapy center on November 6, 2014 in Eastern al-Ghouta, a rebel-held region outside Syria's capital of Damascus. Mustafa, 13, had his legs' tendons cut after he was injured in an airstrike four months before. Medical care in Syria has been disintegrated due to the ongoing conflict that erupted in March 2011. #

Syrians try to rescue wounded people from a burning building following a reported airstrike by government forces on the Kalasa neighborhood of the northern Syrian city of Aleppo on November 12, 2014. #

Syrian Kurdish fighter Delkhwaz Sheikh Ahmad, 22, sits at his brother's house in Suruc, on the Turkey-Syria border, on October 17, 2014 as he prepares to leave for Kobani, Syria, to rejoin the fighting. The father of two is a member of the People's Protection Units, also known as YPG and is fighting against ISIS militants in Kobani. Every few weeks, he takes a couple of days to cross the border into Turkey to visit his family that had evacuated. #

Workers wrap the bodies of dead fighters loyal to Syrian President Bashar al-Assad at a morgue in Aleppo on October 30, 2014. The opposition Free Syrian Army said it killed the men near Aleppo city and that some of the dead had Iranian and Afghan nationalities. Rebels said the bodies are being preserved so they can be used in exchange for their own fallen comrades who are in the hands of the government. #

Men walk along a dark street at night in eastern al-Ghouta, near Damascus on November 19, 2014. Residents in Eastern al-Ghouta have been cut off from the main electricity grid for two years, activists said, relying on generators and other sources of light at night. #

ISIS billboards along a street in Raqqa, eastern Syria, which is controlled by the Islamic State, on October 29, 2014. The billboard (right) reads: "We will win despite the global coalition". #

A general view shows damage inside Shahba Mall, one of the largest commercial shopping centers in Syria, that was targeted by what activists said were airstrikes by forces loyal to Syria's President Bashar al-Assad in northern Aleppo countryside on October 16, 2014. #

A woman accompanies schoolchildren after what activists said were air strikes by forces of Syria's President Bashar al-Assad in the Duma neighborhood of Damascus on October 20, 2014. #

An injured girl receives treatment at a field hospital after what activists said was shelling by forces loyal to Syria's President Bashar al-Assad in Meraba, eastern countryside of Daraa, on November 19, 2014. #

Rebel fighters monitor control screens for any movement of regime forces around the UNESCO-listed citadel where they hold a position on November 3, 2014 in the northern Syrian city of Aleppo. The 5,000-year-old citadel, which towers 100 meters above the rest of the city, is now under the control of rebel fighters. #

A woman screams as she is rescued from a burning building following a reported airstrike by government forces on the Kalasa neighborhood of the northern Syrian city of Aleppo on November 12, 2014. #

Al-Mujahideen army fighters, which operates under the Free Syrian Army, sit in shooting positions inside a damaged room during clashes with forces loyal to Syria's President Bashar al-Assad on the Zeno street front line in Aleppo on November 18, 2014. #

Syrian children attend a class at the Nabaa Al-Hayat center for education and psychological support for children in places undergoing crisis in the rebel-held Eastern Ghouta region on the outskirts of the capital, Damascus, on October 22, 2014. Overall, some 4,000 Syrian schools have been destroyed, damaged or used to house the internally displaced in three years of warfare, leaving the educational system on the verge of ruin, said a report in May by the Damascus-based Syrian Center for Policy Research in conjunction with the UN Development Program and the UN Palestinian refugee agency. #

A rebel fighter runs through dust towards an area damaged by what activists said were barrel bombs dropped by warplanes loyal to Syria's President Bashar al-Assad in Aleppo's al-Shaar neighborhood on November 6, 2014. #

A girl cries during the funeral of 19 year-old Syrian Kurdish fighter girl Perwin Mustafa Dihap who died after being wounded during fighting against ISIS forces in her home town of Kobani, in Suruc, on the Turkey-Syria border, on November 7, 2014. #