After Islamic State, who will foot Iraq's $100 billion reconstruction bill?

Abdulsattar al-Habu, the director of Mosul municipality and reconstruction adviser to Nineveh province, where the city is located, made the warning as the city lies under tons of rubble and people's home and shops remain laced with explosives and unexploded bombs where IS made its last stand against a US-led coalition and Iraqi forces.

While the defeat of IS brought an end to three years of death and destruction across northern and western Iraq, Baghdad estimates $100 billion is needed nationwide to rebuild.

Those in Mosul say that amount is needed for the city alone, as fears that corruption and bitter sectarian divisions will drive majority Sunni populations to feel they've been abandoned by the Shia-dominated government, with resentment feeding the next generation of militants.

With the United States telling Iraqis it won't pay for a massive reconstruction drive, Baghdad hopes Saudi Arabia and other Gulf countries will step up, and Iran may also take a role.

UN projects are repairing infrastructure in nearly two dozen towns and cities, but funding is a fraction of what will be needed. As a result, much of the rebuilding has come from individual Iraqis using personal savings.

In the meantime, many of those who fled IS or the fighting remain uprooted. While 2.7 million have returned, more than three million others cannot and they languish in camps. Worst hit is Mosul; the UN estimates 40,000 homes there need to be rebuilt or restored, and some 600,000 residents have been unable to return to the city, once home to around two million people.

The enormity of the task ahead can be grasped by what has – and hasn't – happened in Ramadi, which was liberated from IS two years ago. More than 70 percent of the Anbar provincial capital remains damaged or destroyed, according to the provincial council.

Nearly 8,300 homes – almost a third of the houses in the city – were destroyed or suffered major damage, according to UN Habitat. Repairs have begun on only three of the five damaged bridges over the Euphrates River. Three-quarters of the schools remain out of commission.

The Anbar provincial council holds its meetings in a small building down the street from the pile of rubble that was once its offices.

Ahmed Shaker, a council member, said, "When we ask the government for money to rebuild, they said: 'Help yourself, go ask your friends in the Gulf" – a reference to fellow Sunnis.

We fought Islamic State (Daesh) on behalf of the whole world. Now is the time for them to stand with Mosul

The main engine for rebuilding has been the UN development agency, known as UNDP, which runs a stabilisation programme rehabilitating infrastructure and some homes.

But funding is far lower than what Iraq says it needs. So far, stabilisation has received some $392 million. The United States and Germany are the top two donors, at $115 million and $64 million respectively.

Overall, Washington has contributed $265 million to reconstruction since 2014, on top of $1.7 billion in humanitarian assistance – compared to $14.3 billion it spent in fighting IS in Iraq and Syria.

Baghdad had expected American money would flow in after the defeat of IS, said a senior US official who regularly meets with Iraqi leadership. But Secretary of State Rex Tillerson has said the United States is no longer in the business of "nation-building."

"We just tell them, no, it's not going to happen," the US official said.

The official said many in Washington believe past efforts in Iraq didn't yield adequate returns and there is little appetite for large international reconstruction projects. After the 2003 toppling of Saddam Hussein, the US pumped $60 billion over nine years into Iraqi reconstruction. Critics say the money did little to prevent political disarray and the rise of militants in Iraq.

Douglas Silliman, the US ambassador to Iraq, blamed destruction squarely on IS fighters.

"Had they not been here, had they not conducted a completely brutal and inhumane campaign against the Iraqi people, this destruction would not have happened," he said.

Amar Ismail Brahim, one of the few in Mosul's Old City who have managed to reopen a shop, also blames the militants. But he says the US and the West have an obligation to back rebuilding.

"We fought Daesh on behalf of the whole world," he said, using the Arabic acronym for the group. "Now is the time for them to stand with Mosul."