Fallujah was the first major Iraqi city captured by ISIS, initially seized back in January 2014. Today, the western Iraqi city is home to an estimated 90,000 people — who, according to a Friday report, are trapped and facing a serious risk of starvation. And it seems that America's allies in Iraq are at least partly to blame.

That's according to Iraq Oil Report, a subscription journalism service that does granular reporting on Iraqi affairs. The story's lead reporter, Jamal Naji, is a Fallujah native and maintains a number of connections inside the city (ISIS has banned Fallujah residents from using cellphones and the internet).

Naji's contacts describe a life in Fallujah where citizens endure vicious ISIS rule and a constant fear of being killed by shells launched into the city by Iraqi military forces. Take, for instance, the tragic story of one man reported by Naji and his colleagues:

One man in the Nazal neighborhood of Fallujah was driven insane after a mortar shell landed on his house, killing his wife and only son. According to one of his relatives, he began screaming insults at Abu Bakr al-Baghdadi, the self-proclaimed caliph leading the IS organization – a crime which earned him an execution by beheading in Masalon Square in the city's old market. The man's offending words were: "Shit on you, Abu Bakr al-Baghdadi. May Allah take revenge on you and Daesh."

The city is facing a severe food shortage. Some residents have seen a 50-kilogram bag of flour go for as high as $4,166 (it costs about $7.50 in the US). Human Rights Watch, along with Iraq Oil Reports, reports incidents of children and adults starving to death or dying of complications from malnutrition.

"Food is so scarce," Naji and his co-authors write, "that many people have resorted to eating grass."

Iraq Oil Report and HRW both say that it's not just ISIS to blame: The Iraqi government and government-aligned Shia militias also bear responsibility for the situation.

The Iraqi government and its militia allies, not yet able to take Fallujah, have set up a siege around the city, attempting to starve out ISIS.

While it's not illegal under international law to besiege enemy forces, it is illegal to lay siege to a populated area. And it seems like that's what's happening: Two Iraqi officials told Human Rights Watch that Iraqi forces "are keeping shipments of food and other goods from reaching the city."

The Iraqi government, to its credit, has attempted to open humanitarian corridors through which aid could be distributed directly to Fallujah residents without going through ISIS. But ISIS wouldn't allow it, and the Iraqi government has let the siege continue.

"Residents in the city confirmed that the local government had tried to open three routes out of the city, but they were discovered and booby-trapped by IS militants," Naji and his compatriots find.

To make matters worse, residents can't flee. ISIS refuses to let people out in large numbers, as it would make their caliphate look like it's collapsing.

"Civilians inside Fallujah have been unable to leave," Human Rights Watch reports. "Three people with connections in Fallujah informed Human Rights Watch in late February that ISIS had executed a family trying to leave. Their extended family revolted against ISIS, and ISIS then jailed more than 100 men taking part."

This is what a proxy war looks like

Sieges have become sadly common in the Middle East of late. The Assad regime has routinely used them in Syria as a weapon against rebel populations, as have (to a much lesser degree) ISIS and rebel factions.

The most notable such case was the city of Madaya, where an Assad-imposed siege became so severe that residents were reduced to killing their dogs and cats for food. Assad's forces began letting aid through after an international outcry, but many residents had already suffered terribly, and many had died.

In Iraq, large-scale sieges have been less common, but perhaps it was only a matter of time.

The Iraqi military has a well-earned reputation for callousness in the face of civilian casualties; it has shelled populated areas a number of times in recent years, as it currently appears to be doing in Fallujah. The Shia militias that are allied with the Iraqi military have been credibly accused of ethnic cleansing and other violence directed at civilians.

These are the groups the United States has aligned against ISIS. Because the US cannot commit its own ground troops in large numbers — neither the American nor Iraqi publics would allow it — it's forced to rely on local forces to beat back ISIS, both in Syria and Iraq.

If we're apportioning blame for the suffering of civilians in Fallujah, ISIS deserves the bulk of it. And thankfully, Iraqi forces are pushing ISIS back across Iraq, and have put the group on the path to ultimate defeat.

But as terrible as ISIS is, its opponents have proven themselves quite capable of human rights abuses as well.