Updated to show further reporting and to clarify the delineation between Ansar al-Sunna/Ansar al-Islam during the Iraq War.

Iraq is under siege and the Islamic State of Iraq and Syria is getting all the publicity. The well-branded al-Qaeda-inspired group has been prevalent in the news since Mosul fell last week, yet for all the headlines, ISIS is apparently only one group of many currently fighting the Iraqi army.

As AFP described Thursday, ISIS is the leader of a coalition composed of an eclectic mix of Iraq war holdovers and unaffiliated tribesmen aligned against Prime Minister Nouri al-Maliki’s government. These are some of the primary groups said to be aligned with ISIS.

Army of the Men of the Naqshbandiyah Order (JRTN):

According to report released by the Combating Terrorism Center at West Point in 2011, JRTN formally appeared after Saddam Hussein’s execution in 2006. During the Iraq “surge” in 2007, JTRN took advantage of failing insurgent groups, namely al-Qaeda in Iraq, and increased its strength substantially. At the time of the report’s release, JTRN was assessed to have from 1,500 to 5,000 fighters. JTRN, the report said, is the only insurgent group to have gotten stronger during the surge.

In contrast to other groups that carried out mass killings of Iraqi Shiites and Iraqi army soldiers, JTRN banned such atrocities. Izzat Ibrahim, a former vice president under Hussein who was regarded as one of the primary leaders of JRTN, stated in 2009, “We absolutely forbid killing or fighting any Iraqi in all the agent state apparatus of the army, the police, the awakening, and the administration.”

Aki Peritz, co-author of “Find, Fix, Finish: Inside the Counterterrorism Campaigns that Killed Bin Laden and Devastated Al Qaeda,” noted that JRTN’s status as a Sufi group makes its cooperation with ISIS striking. An “issue is that they are a Sufi group, which is unique in the insurgent firmament. I say unique since al-Qaeda basically considers Sufis heretics, so it’s odd that they’d be working together,” Peritz said.

Jaysh Mohammed:

Jaysh Mohammed, or Army of Mohammed, surfaced in Iraq in 2004. According to GlobalSecurity.org, the group formed ties with former intelligence and security agents of Hussein’s regime after the 2003 invasion of Iraq. An anonymous interview with a member of the Army of Mohammed by the Institute of War and Peace Reporting in 2005 said that the group was composed of Salafists and was aimed at repelling U.S. forces from Iraq. Yet the unnamed fighter in the interview said the group opposed the idea of killing fellow Muslims, “no matter what.”

While prevalent in Iraq during the coalition’s presence after the 2003 invasion, an officer in Maliki’s security office told the AFP that the Army of Mohammed’s role in the recent attacks has been “limited.”

Ansar al-Sunna:

“Ansar al-Islam is an al-Qaeda linked, Iraqi Kurdish jihadist group that was founded in 2001 when two smaller Kurdish jihadist groups merged operations together,” according to Aki Peritz. “For a while, AAI (which changed its name to Ansar al-Sunna, then changed it back) were for a time on par with AQ I… they carried out the worst single attack on U.S. personnel during the entire war — they snuck a suicide bomber into the mess hall at FOB Marez in 2004, killing 22 U.S. servicemen and contractors.”

A Stanford University map of militant organizations reports that Ansar al-Islam primarily attacked foreign targets strictly within Iraq, yet did not acknowledge the post-2003 Iraqi government as legitimate.

In 2010 after a slew of defections and attacks on their leadership Ansar al-Islam’s leader, Abu Abdallah al-Shafii, was captured. “They still carry out operations, but they are a shadow of what they used to be at the beginning of the [Iraq] war,” Peritz said.

While many of these groups differ ideologically from ISIS, they are still communicating on some levels. “Even if they differ among themselves, they are coordinating and exchanging information,” Saddam Anwar Mahmud Khalaf al-Juburi, a military expert and former general under Hussein, told the AFP. They “are supporting ISIS in this phase because (they think) the enemy of my enemy is my friend.”