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

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

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 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

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

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

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