The writer is Washington director at Human Rights Watch.

The traffic on the road to Tuz Khurmato, a town about an hour south of Kirkuk, was light on a recent morning when we set out to meet senior officials from the Kurdish security forces, the pesh merga. Their fortified bases, lean-tos flying various Shiite militia flags and makeshift camps for displaced families dotted the side of the highway. Official Iraqi security forces were nowhere to be seen, even at checkpoints.

Inside a dusty office at the pesh merga base, a field commander relayed what he had seen during recent weeks of fighting. “They don’t respect human rights, they arrest anyone,” he said. “They kill, they behead, they burn houses.” He was referring not to the Islamic State but to the government-backed Shiite militias alongside whom the pesh merga are fighting the Sunni extremist group in an uneasy marriage of convenience.

The lines between Shiite militias and official security forces have been blurred for years. But with the Iraqi army’s near-total collapse this summer, their strength has increased. Politicians, security force personnel and civilians alike have told Human Rights Watch that these militias “control security” throughout much of Iraq, a point only reinforced by the recent appointment of Mohammed Ghabban, a Shiite politician with strong links to the Badr Brigade, a notorious militia, as Iraq’s interior minister.

In certain parts of Iraq under siege by the Islamic State, the militias continued the fight even after U.S.-led coalition airstrikes shifted to other targets. They did this primarily by attacking Sunnis who didn’t flee the Islamic State advance, considering any remaining families “collaborators,” and ransacking, burning and even demolishing scores of Sunni villages. In some cases, they traveled from village to village in U.S. Army-issued Humvees, which were probably obtained from the Iraqi government.

This relentless arson and pillaging has resulted in death, destruction and, according to local sources, the displacement of more than 7,000 families in recent months. When we pulled over to the side of the highway to speak with a family living in an abandoned strip mall, a man in his late 40s told me, “I am no more afraid of Daesh” — the Arabic acronym for the Islamic State — “than I am of the Shiite militias and the Iraqi government.”

This lawless behavior, of course, is not a new phenomenon but a pervasive part of post-Saddam Hussein Iraq. A congressionally mandated U.S. report from 2007 presciently concluded that “sectarian militias are a fact of life in Iraq. They pose as much danger as al Qaeda in Iraq and may even be a greater threat to Iraqi’s long-term stability.”

Over the past year, government-backed militias have increased kidnapping and killing of Sunni civilians throughout Baghdad, Diyala and Babil provinces, seriously escalating sectarian violence. Even in areas where Iraqi security forces are still somewhat intact — such as Anbar province — they are increasingly led by militias, mainly Kitaeb Hezbollah and Asaib Ahl al-Haq.

In Irbil, I met with an imam and former businessman who recently fled Fallujah because of the anti-Islamic State campaign. He painted a vivid picture of civilians under siege: Since at least July, there has been no running water and no electricity in Anbar province. The absence of running water forced people to drink from a contaminated river, which made people sick. As a result, many Fallujans end up in the hospital but stay only briefly because the hospital itself has become a target for the Iraqi army.

Disturbingly, the imam made clear that the Iraqi air force is still using indiscriminate “barrel bombs” to “go after ISIS” in Fallujah, despite instructions from Baghdad to stop using them. Other governments, including that of the United States, have condemned the use of these horrendously destructive bombs across the border in Syria but have said nothing about them in Iraq. His phone contained a collection of grisly photos — including some from an attack that killed 14 in a family of 20, most of them children.

Many Fallujah residents who initially fled the fighting in Anbar have had to return home because they’ve run out of resources and receive little or no government or international assistance. Back at home, they’ve faced the perfect storm of death: Homes are so hot without electricity that most families sleep outside, even if it means a greater risk.

As the United States and other countries engage in a campaign President Obama said is intended to “degrade and ultimately destroy” the Islamic State, the armed group’s cruelty and swift territorial gains have perpetuated a double standard among coalition members who have joined the effort. Indeed, by turning a virtual blind eye to the abuses committed by Iraqi government forces and its proxy militias, key partners may be helping to push reluctant Sunnis into the Islamic State camp.

A more balanced approach would acknowledge atrocities by all sides while exerting greater pressure on the Iraqi government to carry out long-overdue reforms — including genuinely inclusive politics and steps to overhaul the criminal justice system. It would mean urging the Iraqi government to take an unambiguous and public step away from battlefield tactics that violate the laws of war and to commit publicly to security sector reform — including a plan for meaningful accountability.

The United States has tried much of this before — and at great cost — but it clearly failed. Things need to be different this time, which means making clear that achieving genuine stability in this unstable region won’t be gained by protecting one group at the expense of another. As the fighting continues and the atrocities mount, the path for doing something about that reality is fading fast.