What is ISIS?

by researchers at Inform



  • The group calling itself Islamic State in Iraq and Syria (shortened to Isis or Islamic State) is a militant movement that developed after the US-led military invasion of Iraq in 2003.
  • It rejects existing notions of the nation-state in favour of what it defines as the ultimate Islamic polity – the caliphate, an area controlled by a caliph (Muslim ruler).
  • It differs from other militant Islamist groups in its claim that it established the caliphate in 2014. The caliphate was declared defeated by Syrian Democratic Forces in March 2019. This does not, however, signal the end of Isis, which remains an insurgent group without a territory. The Easter Sunday attacks in Sri Lanka on 21 April 2019 that killed 359 people and injured 500 were carried out by suicide bombers said to be controlled by Isis.
  • Isis is characterised by its use of excessive violence, against both Westerners and other Muslims whom it perceives as in opposition.
  • Isis also has significant influence online – its own propaganda materials are slick and well-distributed and its network includes the social media profiles of the fighters themselves, preachers on YouTube and fans who create the aura of “jihadi cool” 1.
  • Before 2019, Isis was estimated to have about 30,000 to 40,000 members who have sworn an oath of loyalty (bay’ah), as well as additional helpers and supporters. According to some estimates, Isis could muster 200,000 troops but not all of these would be fighters who have pledged sole loyalty to it.
  • It is estimated that 70 per cent of Islamic State’s suicide attacks can be attributed to foreign fighters 2.


  • The Islamic State has its origins in an earlier movement, al-Qaeda in Iraq (AQI), founded by the Jordanian-born Abu Musab al-Zarqawi, who pledged allegiance to Osama bin Laden, the Saudi-born leader of al-Qaeda.
  • Zarqawi and bin Laden were both mujahideen – veterans of the anti-Soviet war in Afghanistan in the 1980s when they received financial, military and political support from the US, Pakistan, and Saudi Arabia.
  • By the early 2000s, and especially after the al-Qaeda attacks of 9/11, the mujahideen became targets of the US.
  • In 2006, Zarqawi was killed in a US military strike, leaving a leadership vacuum
  • Within months the group announced the establishment of the Islamic State of Iraq (ISI), led by Abu Umar al-Baghdadi, its “commander of the faithful”. A strained relationship with al-Qaeda continued: al-Qaeda leaders criticised both Zarqawi and Baghdadi for their lack of communication and co-ordination.
  • Baghdadi was killed in a joint US-Iraqi raid near Tikrit in April 2010.
  • Within a month, ISI appointed a new leader, Abu Bakr al-Baghdadi, who assumed the title “commander of the faithful”.
  • In 2011, during the Syrian civil war, Baghdadi sent a contingent to Syria to form Jabhat al-Nusra (the Salvation Front) – now known as Tahrir al-Sham (Levant Liberation Committee) or al-Qaeda in Syria.
  • ISI then became Isis or Isil (Islamic State in Iraq and the Levant).
  • By the end of June 2014, Isis conquered the city of Mosul and declared the caliphate there, with Baghdadi as caliph.
  • The United States began military interventions against Isis at the request of the Iraqi government.
  • From 2014, following the US-led military campaign, Isis escalated violence against Westerners.
  • In 2014 and 2015, the official Isis spokesman Abu Muhammad al-Adnani called on supporters to kill Westerners all over the globe – Americans, Canadians, Australians, and their allies, both civilians and military personnel 3.
  • Isis began circulating videos of beheadings, including those of Western aid workers and journalists.
  • Also from 2014, individuals or “lone wolves” inspired by the Isis began launching attacks in Western Europe, North America and Australia. Isis advocates improvisation, including smashing people’s heads with rocks, wielding knives, using cars or other vehicles to run people over, throwing victims off high places, and even choking or poisoning them 4.
  • Isis-inspired attacks have since taken place in countries with Muslim-majority populations beyond the Middle East and North Africa, including Bangladesh, Malaysia and Indonesia.
  • From 2014, Isis has suffered military and territorial defeats at the hands of the US-led coalition forces and the Iraqi and Syrian forces.
  • Isis lost control of Mosul in July 2017 and Raqqa in October 2017.
  • On 23 March 2019, Syrian Democratic Forces declared the Isis caliphate defeated.


  • Isis is frequently described as Wahhabist, Salafist and jihadist. All these descriptions are disputed.
  • Wahhabism refers to the religious movement founded in the Arabian Peninsula by the 18th-century reformer Muhammad ibn Abd al-Wahhab. Its main objective was the purification of faith and worship.
  • Salafism is often used interchangeably with Wahhabism. It is an approach to Islam that invokes the literal interpretation of religious texts and a return to the traditions of the pious companions (al-salaf al-salih) of the Prophet Muhammad.
    • However, there is much diversity within Salafism: “quietist Salafis”, the majority in the West, are non-violent and neither are they clandestine – Salafis are well-known for their eagerness to explain their teachings to anyone who is interested 5.
  • Jihadism can refer to “holy war”. However, its semantic meaning in Arabic basically means to strive, exert, or take extraordinary pains. In the Islamic tradition, the term “jihad” is often used without any reference to warfare. As a term to describe militant Muslim groups, “jihadism” is a modern, Western
  • Like al-Qaeda, the official doctrines of Isis do not differ greatly from those of Saudi Arabia, which it nevertheless considers an enemy state. For example, its Islamic criminal law (hudud) penalties are nearly identical to those upheld by the Saudis, including: death for blasphemy, homosexual acts, treason, and murder; death by stoning for adultery; 100 lashes for sex out of wedlock; amputation of a hand for stealing 6.
  • The main difference between Isis and al-Qaeda is that the latter focuses upon defeating Western powers – the “far enemy” – before the caliphate can be established. Isis, on the other hand, insists on vanquishing “near enemies” – Shia Muslims and Muslim governments that collude with the West – by establishing the caliphate first 7.
  • Underlining this difference between the two groups is also Islamic State’s far more explicit apocalypticism.
    • Isis draws upon apocalyptic prophecies to construct its own vision of the caliphate and the Mahdi (messianic redeemer), and to justify its brutality.
    • Its propaganda materials are filled with references to the End Times – which are particularly persuasive in attracting foreign fighters 8.
    • Its flag, for example, is inspired by traditional accounts that the Prophet’s flag was a black square made of striped wool. The flag’s colour also resonates with a set of apocalyptic hadiths (stories about the Prophet) of soldiers fighting under black flags coming from the East 9.
    • There are specific places named in various End-Time prophecies, with many located around Damascus in modern-day Syria 10. This is why Isis forces fought viciously to gain control of Dabiq in northern Syria, despite its lack of military importance (although they were driven out by the Turkish army and Syrian rebels in 2016).
    • Isis also relies upon apocalyptic prophecies to justify and promote its use of extreme violence. For example, its beheading of Coptic Christians in Libya in 2015 was described as part of a war with Christianity that would last until Jesus descends from Heaven [1]1; and Isis has also heralded the return of slavery – the taking of Yazidi women as sex slaves – as a sign of the coming Day of Judgment based on the hadith: “One of the signs of the Last Hour is that the slave-girl will give birth to her master” 12.

Inform is an independent educational charity providing information about minority religions and sects. This is an edited version of a research article on their website https://censamm.org/resources/profiles/isis-islamic-apocalypticism



Professor Peter Neumann, Department of War Studies, King’s College London, and director of the International Centre for the Study of Radicalisation

Dr Shanon Shah, Department of Theology and Religious Studies, King’s College London

Dr Simon Mabon, Department of Politics, Philosophy and Religion, Lancaster University

  1. Neumann 2016: 124
  2. Neumann 2016: 104
  3. Bunzel 2015: 36
  4. Neumann 2016: 132
  5. (Inge 2017: 8).
  6. McCants 2015: 136
  7. Bunzel 2016: 13
  8. McCants 2015: 147
  9. Beattie 2013: 89
  10. McCants 2015:100
  11. McCants 2015: 106
  12. McCants 2015: 112

Neumann, Peter R. (2016) Radicalized. I.B. Tauris, London.

Bunzel, Cole (2016) The Kingdom and the Caliphate: Duel of the Islamic States. Carnegie Endowment for International Peace.

Bunzel, Cole (2015) From Paper State to Caliphate: The Ideology of the Islamic State (No. 19), The Brookings Project on U.S. Relations with the Islamic World. The Brookings Institution, Washington.

Firestone, Reuven (1999) Jihad: The Origin of Holy War in Islam. Oxford University Press, Oxford.

Inge, Anabel (2017) The Making of a Salafi Muslim Woman: Paths to Conversion. Oxford University Press, New York.

McCants, William (2015) The ISIS Apocalypse. St Martin’s Press, New York.Hugh (2013) ‘The Mahdi and the End-Times in Islam’ in: Sarah Harvey and Suzanne Newcombe (Eds.), Prophecy in the New Millennium: When Prophecies Persist, Ashgate Inform Series on Minority Religions and Spiritual Movements. 89-103. Ashgate, Farnham.

Mabon, S. and P., Royle (2016) The origins of ISIS: the collapse of nations and revolutions in the Middle East London: I. B. Tauris