“The Haqqani network’s centrality to the region’s conflict economy and the role it has played as a local conflict mediator over multiple decades have helped to solidify the Haqqani’s status in the tribal areas. At the local level in Pakistan, relations between the Haqqani network and local militant groups are deeply integrated and interdependent.”

The Haqqanis have resources, tribal connections, local support, land, manpower and financing that will persist long after U.S. and NATO combat troops withdraw from Afghanistan at the end of 2016. As the Pentagon acknowledged in its own report to Congress on the state of the Afghan conflict, “[t]hey [the Haqqani network] will likely remain the most significant threat to coalition forces in the post-2014 noncombat mission, especially if they are not denied sanctuary in Pakistan.”

5. Kataib Hezbollah:

Large groups of men wearing baklavas raid a house in the dead of night, take several young men into custody, and drag them to a field where they are tortured and executed with bullets to the head. Sounds like the menacing behavior of ISIL, right? Well, there’s another organization using the same exact tactics—wreaking destruction in Iraq and tearing at the country’s social fabric in the process. This time, it’s a Shia militia with close ties to the Iraqi government, the Iraqi army and Iran.

Kataib Hezbollah, formed in 2006 or 2007, was once known for ambushing U.S. troops during their patrols of Iraqi neighborhoods and for placing armored-piercing IED’s on the roads that U.S. Humvees would use. The killing of U.S. soldiers and the frequent rocket attacks that KH would launch directly into Baghdad’s Green Zone landed the group on the U.S. foreign terrorist organization list in 2009. “KH has threatened the lives of Iraqi politicians and civilians that support the legitimate political process in Iraq,” the State Department noted in its designation. It’s hard to argue that this band of Shia fighters has changed their behavior five years later.

In fact, due to the unpredictable collapse of the Iraqi army, Kataib Hezbollah has only grown more powerful and its name has only increased in relevance. The Iraqi government—first under former prime minister Nouri al-Maliki and now under Haider al-Abadi—has come to depend upon informal Shia militias like KH for reinforcing an army that is struggling to chip away at ISIL’s territorial expansion in northern and western Iraq. Militias like KH are now the tip of the spear for the Iraqi counterattack, a fact that was demonstrated quite clearly during the capture of Amerli, when Iran-backed militia groups, Kurdish peshmerga forces and U.S. warplanes teamed up in a tactical alliance to drive ISIL from the area.

Unfortunately, with dependency comes a lack of accountability. Human Rights Watch and Amnesty International, the world’s two premier human-rights organizations, have both documented appalling cases of brutality and violence from KH and its Shia allies. Any Sunni even remotely suspected of tolerating ISIL’s presence is arrested without charge or explanation and either tortured in one of Iraq’s notorious prisons or killed on the spot. It’s not uncommon for a Sunni to be simply kidnapped and threatened with death unless their family members pay a high price for a release. All of these abuses and war crimes occur without any punishment or investigation by the Iraqi army or the government in Baghdad, perhaps fearing that KH and similar militias like Asaib ahl al-Haq will turn against the national authorities in retaliation.

If ISIL elicits shivers and fear in the heart of an Iraqi Shia, Kataib Hezbollah produces the same emotion in an Iraqi Sunni.

Daniel R. DePetris is a senior associate editor at the Journal on Terrorism and Security Analysis. He has also written for CNN.com, Small Wars Journal and The Diplomat.