Profile: Islamic State in Iraq and the Levant (ISIS)
The Islamic State in Iraq and the Levant is a jihadist group active in Iraq and Syria.
It is widely known by the acronym ISIS, in which the final "S" stems from the Arabic word "al-Sham". This can mean the Levant, Syria or even Damascus but in the context of the global jihad it refers to the Levant.Roots in Iraq
When the group was formed in April 2013, it was initially presented as a merger between the al-Qaeda-affiliated Islamic State of Iraq (ISI) and a Syrian jihadist rebel group, the al-Nusra Front.
However, the announcement of the merger by ISI leader Abu Bakr al-Baghdadi was immediately rejected by the al-Nusra Front.
Two months later, al-Qaeda leader Ayman Zawahiri reportedly ordered the merger to be annulled.
ISIS has since become one of the main jihadist groups fighting government forces in Syria.
Its precise size is unknown, but it is thought to include thousands of fighters, including many foreign jihadists.
ISIS has claimed responsibility for a number of attacks in Syria. In August, it was reported to have played a role in taking control of an important military air base in Aleppo province.
It also has a presence in a number of towns close to the Turkish border in the north of the country.Inter-rebel tension
The group has been operating independently of the al-Nusra Front and has had a tense relationship with other rebels in Syria.
In July, a commander of the Western-backed Free Syrian Army (FSA) was reportedly shot dead by ISIS fighters in the coastal province of Lattakia.
There were also reports of deadly clashes between the two groups in the north-western province of Idlib.
In the most recent sign of continuing tension, ISIS seized the northern town of Azaz from the FSA on 18 September.
There has also been friction with other Islamists. Earlier this month, ISIS was accused of killing a prominent member of the Syrian Islamist rebel group Ahrar al-Sham.
ISIS, which is still led by Abu Bakr al-Baghdadi, continues to be active in Iraq, too.
In August, it claimed responsibility for a series of bomb attacks in Baghdad and other areas of Iraq in which dozens were killed.ISIS strongholds in rebel-held and contested areas