When the Islamic State of Iraq and the Levant (Isil) escalated its fight against fellow rebels in Syria late last year, private donors in the region were rattled. For three years, a network of clerics and Sunni politicians had funded anti-regime groups in Syria, including other jihadi factions such as Ahrar Al Sham and Jabhut Al Nusra – groups now at war with Isil.

First, the donors tried reasoning with Isil: all rebels should work together against Syrian President Bashar Al Assad. In October, Kuwaiti donor Mohammed Haif announced on Twitter that there had been a meeting of elders trying to reason with Isil members and their families. Another Saudi cleric, Yousef Bin Abdallah Al Ahmad, tried to broker peace between the leader of Isil and Salafi brigade Ahrar Al Sham.

But by early 2014, it was clear the talks had failed. Haif warned Isil to withdraw from Syria. Other donors alleged sedition: Isil is “actively seeking to burn all the gains of the Syrian jihad,” another Kuwaiti donor, the cleric Shafi Al Ajmi, wrote in a Tweet.

In the last two weeks as Isil has seized large swathes of Iraq, however, the donor community is regrouping. Isil’s military success appears likely to attract new support to its cause, even from former critics who want to back a winner. Yet that very military success – and the spoils that it brought to Isil and its Sunni allies in Iraq – makes the group less dependent on outside sponsors and ultimately harder to control.

Private donors are estimated to have given hundreds of millions of dollars to Syrian rebels since 2012 which until last year did not have a law on the books prohibiting the financing of terror.

Whatever the nuances of funding of Syrian fighters, Iraq’s Shiite-dominated government is ready to believe the worst. In a strongly worded statement, Iraq’s cabinet accused Saudi Arabia of supporting Isil and other groups in Iraq and said the Saudi government “should be held responsible for the dangerous crimes committed by these terrorist groups.”

Saudi Arabia has denied the accusations. On Wednesday, the state news agency said that Saudi deputy crown prince Muqrin Bin Abdul Aziz Al Saud was meeting with the Iraqi foreign minister to discuss the regional situation.

Indeed, it and other Gulf states fear that Isil is recruiting their nationals who may eventually target the homeland, just as Al Qaida did in the past. Saudi Arabia named Isil an official terrorist organization earlier this year and increased penalties for anyone caught supporting or fighting with them.

“Isil and some of these other groups positioned themselves as enemies of the Gulf states,” says Emile Hokayem, Bahrain-based senior fellow at the International Institute for Strategic Studies. “They never miss an opportunity to attack Saudi Arabia or other Gulf states.”

The official position of governments like Saudi Arabia is one thing. But Some of the same donors who once decried Isil in Syria are celebrating their Iraqi victory.

“What is happening in Iraq is a people’s revolution against oppression and tyranny,” Kuwaiti donor Hajjaj Al Ajmi, wrote on Twitter on June 16. A young Sunni cleric, Ajmi has spent much of the last two years travelling in and out of Syria to visit the brigades he has funded.

One reason why donors are reconsidering is the success Isil has had in Iraq. They see the group’s rapid advance in northern and western Iraq as a broader and legitimate Sunni revolt against Prime Minister Nouri Al Maliki’s Shiite Islamist ruling circle. Numerous tribal groups and other militias have joined Isil to drive out Iraqi government troops from Mosul, Tikrit, and other cities.

“What is happening now on the ground in beloved Iraq is the result of the policies of oppression and exclusion, corruption” by the Iraqi government, argued a June 14 statement from the International Union of Muslim Scholars, an international Muslim Brotherhood-linked group led by Qatar-based cleric Yousef Al Qaradawi. Salafi groups in Kuwait, the UAE, and Saudi Arabia issued a joint statement on June 13 accusing the Iraqi government of “turning [the country] into a failed state.”

If Isil’s advance in Iraq does attract new private donations from the region, it may not be to Isil itself, which is already flush from extortion and protection rackets in northwest Syria and Iraq’s Anbar province. Add in oil smuggling and bank raids in Iraq, and the group looks increasingly self-sufficient.

“Donor support probably hasn’t been significant, at least in recent years,” says a Doha-based financial analyst, who asked not to be named. “Isil’s goal to govern, including self-financing, is what sets it apart from the others.”