Fighter of the al-Nusra Front. (Rami Al-Sayed/AFP)

When the United States launched airstrikes in Syria this week, they targeted not only the extremists of the Islamic State, but positions manned by a shadowy organization with al-Qaeda links dubbed the "Khorasan Group." Though our understanding of the group remains murky, it joins a whole constellation of al-Qaeda offshoots in the Middle East.

What is striking about many of these groups is their recent emergence. Some were founded to adapt to the challenge of pro-democracy protesters in the Arab Spring (such as Ansar al-Sharia in Yemen), while others are a reaction to the intensifying competition among terror groups in the Middle East (one example would be the Khorasan group).

If we included other regions, such as further east in South Asia or in Africa, the number of organizations would rise significantly. Here is a selection of Middle Eastern groups.

Jabhat Al-Nusra
Two members of the Nusra Front speak in front of U.N. peacekeepers in an unknown location, in this still image from video said to be recorded by the al-Qaeda-backed al-Nusra Front on September 9, 2014 and obtained by Reuters on September 11, 2014. Al Jazeera television said on Thursday the al Qaeda-backed Nusra Front group released U.N. peacekeepers it seized two weeks ago on the Golan Heights. The group on Wednesday posted a video on its Twitter and YouTube accounts in which the hostages, from the South Pacific nation of Fiji, said they expected to be freed soon. The head of Fiji's army said on Wednesday the Islamist militant group had dropped all of its demands to free the 45 hostages, but at least slightly back-pedaled later in the day as the situation appeared to deteriorate. It was unclear whether the video, carried by the SITE monitoring service, was made before or after the confusion surrounding those comments, but a U.N. source earlier told Reuters that the militants had insisted on such a video as a condition for the peacekeepers' release. REUTERS/Nusra Front via Reuters TV (SYRIA - Tags: CIVIL UNREST MILITARY TPX IMAGES OF THE DAY) ATTENTION EDITORS - NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS Two members of the Al-Nusra Front speak in front of U.N. peacekeepers on Sept. 9, 2014. (Nusra Front via Reuters TV)

The group (translated name: "Victory Front") emerged in 2011 as an offshoot of al-Qaeda in Iraq, which is now known as the Islamic State. Donations from abroad and al-Qaeda in Iraq helped the group gain momentum very quickly — but it has since distanced itself from the Islamic State and pledged its allegiance to the central al-Qaeda network. Al-Nusra was among the groups targeted by U.S. airstrikes in Syria on Tuesday morning.

Abdallah Azzam Brigades
10_10_25_70CAPXAPW9 The Abdullah Azzam Brigades claimed responsibility for a twin bomb attack in Beirut in February 2014. (Mohamed Azakir/Reuters)

The group is an offshoot of al-Qaeda in various locations of the Middle East. According to the U.S. Department of State, the group operates in Lebanon and the Arabian Peninsula, and was formed in 2009. In 2014, it claimed it had fired several rockets into Israeli territory from Gaza. Two years earlier, it had warned Shiites in Lebanon not to join Assad's fight against the Syrian opposition and threatened those who would not comply.

Al-Qaeda in the Arabian Peninsula/Ansar al-Sharia (Yemen)
10_10_25_70CA5T57O2 Leaders of Ansar al-Sharia in Yemen. (AFP/Getty Images)

Ansar al-Sharia in Yemen — an offshoot of al-Qaeda in the Arabian Peninsula —has been targeted by U.S. drone strikes in recent years. According to the BBC, al-Qaeda in the Arabian Peninsula's religious leader views Ansar al-Sharia as a way to attract people to Sharia rule in areas occupied by the militants. In Yemen, various factions belonging to the government in Sanaa, tribes, the Houthis, or al-Qaeda are competing. Ansar al-Sharia puts a strong emphasis on building local support — a model that makes it distinct from other offshoots.

Khorasan Group
muhsin_al_fadhli Longtime al-Qaeda operative Muhsin al-Fadhli leads a group called Khorasan. (State Department)

This group is considered a new al-Qaeda franchise and was described by President Obama as consisting of "seasoned al-Qaeda operatives." Many Western terrorism analysts were taken by surprise when U.S. Director of National Intelligence James Clapper recently compared the U.S. national security threat posed by the Khorasan Group to the one of the Islamic State. According to CNN, the Khorasan Group is planning attacks against the United States. Early Tuesday, the Pentagon said the group had "established a safe haven in Syria to develop external attacks, construct and test improvised explosive devices and recruit Westerners to conduct operations." Its objectives are distinct from other groups: Instead of aiming at overthrowing Syrian President Bashar al-Assad and accumulating land like the Islamic State, the Khorasan group is believed to focus on attacks against Western nations. Other experts contest that the group is just a wing of Jabhat al-Nusra.

Asbat al-Ansar

The Lebanese umbrella organization in Lebanon is believed to be partially financed by al-Qaeda and has publicly announced its support for the group now known as the Islamic State.