Islamic State fighters take part in a military parade along the streets of northern Raqqa province in Syria, June 30, 2014. REUTERS/Stringer 

A resident of Tabqa city touring the streets on a motorcycle waves an Islamist flag in celebration after Islamic State militants took over Tabqa air base, in nearby Raqqa city, Syria, August 24, 2014. REUTERS/Stringer 

Displaced residents from the minority Yazidi sect, fleeing violence from forces loyal to the Islamic State in Sinjar town, walk towards the Syrian border, on the outskirts of Sinjar mountain, near the Syrian border with Iraq, August 11, 2014.
REUTERS/Rodi Said 

Paula (L) and Ed Kassig, parents of U.S. aid worker Peter Kassig who was behaded by Islamic State militants, walk toward microphones before reading a statement to the press in Indianapolis, Indiana, November 17, 2014. The parents asked for prayers for other captives in Syria and Iraq in a brief public statement. REUTERS/Brent Smith 

Smoke and flames rise over a hill near the Syrian town of Kobani after an airstrike, as seen from the Mursitpinar crossing on the Turkish-Syrian border, October 23, 2014. REUTERS/Kai Pfaffenbach 

Relatives of Lebanese soldier Ali al-Sayyed, who was beheaded by Islamic State militants, mourn in the town of Fnideq, northern Lebanon August 29, 2014. Islamic State militants beheaded the Lebanese soldier who was one of 19 captured by hardline Syrian Islamists when they seized a Lebanese border town for few days. REUTERS/Stringer 

Fighters from Islamic State burn confiscated cigarettes in the city of Raqqa, April 2, 2014. REUTERS/Stringer 

A female member of the Kurdish People's Protection Units mourns over the grave of her fellow fighter, who was killed during clashes with Islamic State fighters in Ras al-Ain, Syria, January 28, 2014. REUTERS/Rodi Said 

Militant Islamist fighters ride horses as they take part in a military parade along the streets of Syria's northern Raqqa province, June 30, 2014. REUTERS/Stringer 

Islamic State militants embrace in celebration after taking over Tabqa air base near Raqqa, Syria August 24, 2014. . REUTERS/Stringer 

Free Syrian Army fighters inspect damage from suicide bombers belonging to the Islamic State, whom activists said were targeting the Tawhid Brigade and Al-Fateh brigade headquarters that are under the Free Syrian Army, in Aleppo, Syria, January 12, 2014.
REUTERS/Ahmad Othman 

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

REUTERS/Nour Fourat 

Mother of Islamic State captive Jordanian pilot Muath al-Kasaesbeh holds his picture while sitting in a car, as she takes part in a demonstration demanding that the Jordanian government negotiate with Islamic state and for the release of her son, in front of the prime minister's building in Amman, January 27, 2015. Kasaesbeh was captured after his jet crashed in northeast Syria in December during a bombing mission against the militants. The following week, Islamic State released a video showing Kasaesbah being burned alive in a cage.

REUTERS/Muhammad Hamed 

A cradle left behind by Syrian Kurdish refugees fleeing Islamic State lies at the Turkish-Syrian border, September 27, 2014. REUTERS/Murad Sezer 

An armed motorcade belonging to members of Derna's Islamic Youth Council, consisting of former members of militias from the town of Derna, drive along a road in Derna after the group pledged allegiance to Islamic State, in eastern Libya, October 3, 2014. REUTERS/Stringer 

An Islamic State flag is seen atop a building in eastern Kobani as Kurdish Peshmerga forces fight against Islamic state fighters, November 1, 2014. REUTERS/Yannis Behrakis 

An Islamic State fighter gestures from a vehicle in the countryside of the Syrian Kurdish town of Kobani, after the Islamic State fighters took control of the area, October 7, 2014. REUTERS/Stringer 

A Kurdish Peshmerga fighter inspects the burnt, former media office of Islamic State militants in Sulaiman Pek, after the town was recaptured, in Iraq, September 3, 2014. REUTERS/Ahmed Jadallah 

The body of a man who was killed in a suicide bombing at a mosque, lies at a hospital morgue in Sanaa, March 21, 2015. Suicide bombers killed 137 worshippers and wounded hundreds more during Friday prayers at two mosques in the Yemeni capital Sanaa, in coordinated attacks claimed by Islamic State.


REUTERS/Khaled Abdullah 

Militant Islamist fighters on a tank take part in a military parade along the streets of northern Raqqa province June 30, 2014. REUTERS/Stringer 

Kurdish peshmerga forces look at bones in a mass grave on the outskirts of the town of Sinjar, February 3, 2015. Police said the mass grave contained remains from 25 people belonging to the minority Yazidi sect, apparent victims of Islamic State militants. REUTERS/Ari Jalal 

An Islamic State fighter, waving a flag, cheers as he takes part in a military parade along the streets of Syria's northern Raqqa province June 30, 2014. REUTERS/Stringer 

A child's shoe is seen in front of debris from a Russian airliner which crashed at the Hassana area in Arish city, north Egypt, November 1, 2015. Islamic State has claimed to be behind the downing of a Russian aircraft that crashed in Egypt's Sinai Peninsula, killing 224.


REUTERS/Mohamed Abd El Ghany 

Residents and Lebanese army members inspect a damaged area caused by two explosions in Beirut's southern suburbs, Lebanon November 12, 2015. The Islamic State-claimed attack killed 43 people in two explosions in suicide attacks in a Shi'ite Muslim district of southern Beirut in Lebanon.


REUTERS/Khalil Hassan 

French fire brigade members aid an injured individual near the Bataclan concert hall following fatal shootings in Paris, November 13, 2015. Islamic State claimed responsibility for the attacks, which killed 129 people in Paris, in the worst bloodshed in France since the end of World War Two.

REUTERS/Christian Hartmann 

People mourn outside "Le Petit Cambodge" and "Le Carillon" restaurants a week after a series of deadly attacks in Paris, November 20, 2015. REUTERS/Benoit Tessier 

Flight deck crew work around a Super Etendard fighter jet as a French flag flies aboard the French nuclear-powered aircraft carrier Charles de Gaulle before its departure from the naval base of Toulon, France, to support operations against Islamic State in Syria and Iraq, November 18, 2015. France's Charles de Gaulle aircraft carrier will be deployed

REUTERS/Jean-Paul Pelissier