WHO ARE THEY?
Islamic State is a Sunni militant group whose goal is to build a medieval-style Islamic state, or caliphate, spanning the borders of Iraq and Syria. It has seized a large chunk of Syrian and northern Iraqi territory since early June. On June 29 they proclaimed the territory they control to be an "Islamic State," which is now used as a synonym for the group itself.
ARE THEY THE SAME AS ISIL AND ISIS?
Yes. They used to be called ISIL (the Islamic State of Iraq and the Levant) or sometimes ISIS (the Islamic State of Iraq and Syria or Islamic State of Iraq and al-Sham) due to different translations of the group's Arabic name. Sham can mean "greater Syria" or "the Levant," a traditional name for the eastern Mediterranean region that includes Syria.
WHERE DID IS COME FROM?
After the fall of Saddam Hussein, the group, then called the Islamic State in Iraq, fought U.S. forces as the Iraqi branch of al-Qaeda. Under the leadership of Abu Bakr al-Baghdadi, who now styles himself Caliph Ibrahim, the group split with al-Qaeda's global leadership in 2013 by moving into Syria's civil war – against the wishes of Osama bin Laden's successor, Ayman al-Zawahri – and violently displacing al-Qaeda's main affiliate there, the Nusra Front.
After aligning themselves with Sunni tribes in eastern Syria, they muscled into the fight against the Syrian regime of Bashar al-Assad before turning to battling more moderate rebels for control of territory, exploiting the anti-Assad funding and weapons coming in from the Sunni Arab rulers of the Gulf.
ISIL's first major assault in Iraq was on Mosul, Iraq's second-largest city, on June 10. Since then, it has cemented control over a large swath of Iraq's north, displacing hundreds of thousands of refugees and killing hundreds of Iraqi soldiers and police.
WHO ARE THEY FIGHTING?
- Kurds: The Kurds are an ethnic group spanning parts of Turkey, Syria, Iran and northern Iraq, where Iraqi Kurds have a partly autonomous regional government. Kurdish peshmerga fighters have been on the front lines fighting the Islamists, rallying in particular around Kobani, a Syrian town on the Turkish border that Islamic State sees as strategically vital link between Raqqa, their regional capital, and Aleppo, Syria's largest city.
- Iraqi forces: Iraq's mostly Shia army and sectarian militia groups have fought to retake northern cities from the Islamists.
- Western allies: Several of Iraq's Western allies have pledged military assistance to the Kurds and provided millions in humanitarian aid. Since authorizing targeted air strikes in Iraq on Aug. 7 and Syria on Sept. 10, the United States has led a multinational coalition bombarding Islamic State targets from the air. On Oct. 7, Canada approved a six-month mission to Iraq, including nine military aircraft for targeted air strikes. Ottawa has ruled out deployment of ground troops, but a group of Canadian special-forces troops has been operating in Iraq since September.
- Religious minorities: Islamic State fighters believe non-Sunnis to be apostates, and religious minorities in areas conquered by the group have faced a stark choice to convert or be killed - a threat the Islamists have enforced with crucifixions and beheadings. The Yazidis, a Kurdish minority whose religion is derived from Zoroastrianism, took an especially heavy humanitarian toll, fleeing in the thousands and enduring a days-long siege on Sinjar mountain in August.
WHAT COULD HAPPEN TO THE MIDDLE EAST?
The Islamic State's advance has renewed discussion about whether Iraq and Syria's colonial boundaries will fall apart. This could split Iraq along religious and ethnic lines into three separate regions or even countries: Shia in the south and east, Sunni in the west and part of the north, and Kurdish in the northern areas including Kirkuk and Erbil.
Resurgent Kurdish nationalism in the region has caused friction with Turkey, where a three-decade-long Kurdish insurgency left some 40,000 people dead. Ankara's reluctance to send ground troops to aid in the conflict against Islamic State has fuelled violent civil unrest in Turkey involving sympathizers and critics of the Kurdistan Workers' Party (PKK) and radical Islamists.
With reports from Associated Press, Reuters, Patrick Martin, Mark Mackinnon, Kim Mackrael and Daniel Leblanc