Definition of ISIS and the Islamic State of Iraq and Syria

History and Mission of the Jihadist Group in Syria and Iraq

Battle with ISIS
A Kurdish peshmerga fighter looks on as smoke billows from a combined aircraft, artillery and ground attack to recapture the village of Tiskharab from ISIS in 2016 near Mosul, Iraq. Carl Court/Getty Images

ISIS is a terrorist group whose acronym stands for the Islamic State of Iraq and Syria. Members of the group have carrier out more than 140 terrorist attacks in nearly three dozen countries, killing some 2,000 people since the summer of 2014, according to published reports. Terrorists inspired by ISIS have carried out several deadly attacks in the United States.

ISIS first came to the attention of many Americans in 2014 when President Barack Obama ordered airstrikes against the group and acknowledged that his administration had underestimated the particularly virulent extremist movement in Syria and Iraq. 

But ISIS, sometimes referred to as ISIL, had been around years before it began making headlines across the world for its deadly attacks against Iraqi citizens, its seizure of Iraq's second-largest city in the summer of 2014, its beheading of western journalists and aid workers, and establishing itself as a caliphate or Islamic state.

ISIS has claimed responsibility for some of the worst terrorist attacks across the world since September 11, 2001. The violence committed by the ISIS is extreme; the group has killed dozens of people at a time, often in public.

So what is ISIS, or ISIL? How are the answers to some commonly asked questions.

What's the Difference Between ISIS and ISIL?

View of the Islamic State occupied al-Nouri mosque (dome in background) in the old city of west Mosul, the last area of the city under Islamic State control, in 2017. Martyn Aim/Getty Images

ISIS is an acronym that stands for Islamic State of Iraq and Syria, and it's the most commonly used term for the group. However, the United Nations, Obama and many members of his administration referred to the group as ISIL instead, an acronym for Islamic State of Iraq and the Levant. 

The Associated Press prefers the use of this acronym as well because, as it put it, of ISIL's "aspirations to rule over a broad swath of the Middle East," not just Iraq and Syria.

"In Arabic, the group is known as Al-Dawla Al-Islamiya fi al-Iraq wa al-Sham, or the Islamic State of Iraq and al-Sham. The term 'al-Sham' refers to a region stretching from southern Turkey through Syria to Egypt (also including Lebanon, Israel, the Palestinian territories and Jordan). The group’s stated goal is to restore an Islamic state, or caliphate, in this entire area. The standard English term for this broad territory is 'the Levant.'"

Is ISIS Tied to al-Qaida?

Osama bin Laden appears on Al-Jazeera Television praising the attacks of September 11th, 2001, and defying the United States in its threats to attack Afghanistan's Taliban government, which was playing host to him. Maher Attar/Sygma via Getty Images

Yes. ISIS has its roots in the al-Qaeda terrorist group in Iraq. But al-Qaeda, whose former leader Osama bin Laden masterminded the September 11, 2001, terrorists attacks, disowned ISIL. As CNN reported, though, ISIL distinguished itself from al-Qaeda by being the "more brutal and more effective at controlling territory it has seized" of the two radical anti-Western militant groups. Al-Qaeda renounced any affiliation with the group in 2014.

Who is the Leader of ISIS or ISIL?

His name is Abu Bakr al-Baghdadi, and he has been described as “the world’s most dangerous man” because of his leadership role with al-Qaeda in Iraq, which killed thousands of Iraqis and Americans. Writing in Time magazine, retired Army lieutenant general Frank Kearney said of him:

“Since 2011, there has been a U.S.-funded $10 million bounty on his head. But the worldwide hunt did not prevent him from moving into Syria and last year taking command of the deadliest Islamist group there.”

Le Monde once described al-Baghdadi as “the new bin Laden.”

What is the Mission of ISIS or ISIL?

Tanks from the Turkish Armed Forces are dispatched to the Turkish - Syrian border as clashes intensified with Islamic State of Iraq and Levant (ISIL) militants. Carsten Koall

The group's objective is described here by the Terrorism Research & Analysis Consortium as "the establishment of a world wide Caliphate, reflected in frequent media reports by means of images of the world united under a ISIS banner."

How Big of a Threat is ISIS to the United States?

President Barack Obama
President Barack Obama signs the Budget Control Act of 2011 in the Oval Office, Aug. 2, 2011. Official White House Photo/Pete Souza

ISIS poses a larger threat than many in the U.S. intelligence community or Congress initially believed. In 2014, Britain was very concerned that ISIS would acquire nuclear and biological weapons for possible use against the nation. Britain's Home secretary described the the group as potentially becoming the world's first truly terrorist state.

In an interview with 60 Minutes in the fall of 2014, Obama acknowledged the U.S. underestimated what had been taking place in Syria that allowed the country to become ground zero for jihadists around the world. Previously, Obama had referred to ISIS as an amateur group, or JV team.

"If a JV team puts on Lakers uniforms that doesn't make them Kobe Bryant," the president told The New Yorker.

ISIS has inspired numerous homegrown terrorist attacks in the U.S., including the two people - Tashfeen Malik and her husband, Syed Rizwan Farook - who shot 14 people to death in San Bernardino, California, in December 2015. Malik reportedly had pledged allegiance to ISIS leader Abu Bakr al-Baghdadi on Facebook.

In June 2016, gunman Omar Mateen killed 49 people at the Pulse nightclub in Orlando, Florida; he had pledged allegiance to ISIS in a 911 phone call during the siege. 

ISIS Attacks

Donald Trump speech
President Donald Trump delivers his inaugural address. Alex Wong / Getty Images

ISIS has claimed responsibility for a series of coordinated terrorist attacks in Paris in November 2015. Those attacks killed more than 130 people. The group also said it orchestrated a March 2016 attack is Brussels, Belgium, that killed 31 people and injured more than 300. 

The attacks led the Republican presidential nominee in 2016, Donald Trump, to propose a temporary ban on Muslims from entering the United States. Trump called for a "total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what is going on." 

In 2017, the United Nation's human rights office said ISIS killed more than 200 civilians as members of the terrorist group was fleeing western Mosul, Iraq.