The Most Infamous Terrorist Groups of the 21st Century: The History of the Organizations Behind This Century’s Deadliest Attacks

Since the attacks on September 11, 2001, the world has struggled to define al-Qaeda, an amorphous, growing, and seemingly inexhaustible organization. Once a relatively organized group based in one country with a defined hierarchy and clear leadership, al-Qaeda has transformed into a transnational phenomenon over the last few decades, with branches and affiliates operating in dozens of countries across the world. Many call al-Qaeda an enemy, while some define it as an ideology, and others analyze it as a network. Of course, a small minority takes it up as their cause and an extension of their religion.

Also known as ISIS, Da’esh, al-Qaeda in Iraq (AQI), and a host of other names, the Islamic State in Iraq and the Levant (ISIL) has increasingly gained attention over the years for its brutal tactics and seemingly blatant disregard for human rights, but it has recently dominated the global media spotlight and made headlines when it attacked and seized control of Mosul, the second largest city in Iraq, and drove out an Iraqi army force that was more than five times its size in June 2014. It has since laid claim to various territories throughout Iraq and the Levant, and it has established operational control and maintained administrative structures on both sides of the Iraqi-Syrian border. Most recently, it declared the restoration of a caliphate and renamed itself the Islamic State.

Jabhat Al-Nusra’s formal name is, “Jabhat Al-Nusra li-Ahl al-Sham,” or, the “Victorious Support Front for the People of Sham (or, Syria)” and the group first emerged on the international scene in early 2012 as a localized Syrian affiliate of Al-Qaeda in Iraq. The group has carried out numerous terrorist attacks and kidnappings, and has been involved in a variety of battles against Bashar Assad’s Syrian government forces as well as against other anti-government factions such as ISIL.

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Lydbog: 29. januar 2026