Kurdish Peshmerga soldiers count their money after receiving the equivalent of one month out of several delayed months of salary, at Bnaslawa Military Base in Irbil, northern Iraq.

The Pentagon on Tuesday signed a memo with the Peshmerga ministry to give the Kurdish forces of the autonomous northern region of Kurdistan in Iraq financial and military backing, the local Al-Sumaria News reported.

The Peshmerga, the military force of Kurdistan, is controlled separately by Kurdistan’s two main Kurdish political parties — the Democratic Party of Kurdistan and the Patriotic Union of Kurdistan.

American and Kurdish officials, including Kurdistan’s President Masoud Al-Barazani, attended the signing.

The independent Iraqi Al-Sumaria News reported that the memo also includes paying the salaries for the Peshmerga.

Kurds in Iraq and Syria have gained a reputation as formidable soldiers, and especially their women fighters in their battle against ISIS.

Meanwhile, Al Arabiya News Channel reported on Tuesday that the Peshmerga’s role in the upcoming battle to recapture Iraq’s second largest city of Mosul, is to storm the city from the northern and eastern axis, while Iraqi forces enter from the south.

Mosul was seized by ISIS in a lighting offensive in June 2014.

Professor George Joffe, a Middle East expert from Cambridge University, dubbed the peshmerga forces participating in the upcoming Mosul battle as “essential.”

Joffe said “what the Kurds are saying is if you do not pay our costs, we can not provide you with the forces” on the backdrop of low oil prices, a key natural resource Kurdistan depends on to make its profits.

Asked if the signing of the memo would anger the central government in Baghdad, he said “it is an attack on Iraq’s sovereignty, but it [Baghdad] can not argue against because Americans are paying the bills.”

While Baghdad might not be happy about such memos, the government of Prime Minister Haider Abadi still needs the Kurds to recapture Mosul.

“They absolutely do [need the Kurds],” the professor said. “The problem for the Iraqis is that if they are not using the Kurds, they will be using the Hashed, but they do not want to do that because that will alienate all the Sunnis,” he added, using the Arabic word ‘Hashed’ for the Popular Mobilization Units (PMU), volunteer forces made mainly of Shiites.

Like the Kurds, the PMU has gained a reputation for its hard-hitting and “willing to die” fighters, who emerged after Iraq’s army abandoned the country’s second largest city of Mosul in June 2014. Their power intensified after the Iraqi army then lost Anbar’s Ramadi in May the same year.

However, Sunnis fear the PMU over alleged reports of retaliatory acts following liberation of Sunni areas.

To further back Iraq’s quest in defeating ISIS, Defense Secretary Ash Carter in an unannounced visit to the country on Monday said that the United States will send 560 more troops to Iraq to help strengthen a newly retaken air base as a staging hub for the long-awaited battle to recapture Mosul.

Carter’s day-long visit to Iraq comes on the heels of the two-day NATO summit in Warsaw where allies agreed to expand their military support for the war.

Iraq has also recently recaptured the strategic Al-Qayara air base, south of Mosul, paving the path to claim control over the ISIS-held city again.

In addition to Qayara, Iraqi government troops recently have retaken Ramadi, Fallujah and a number of towns along the route to Mosul.

But ISIS militants still control large swathes of the country and continue to launch deadly attacks, including a massive suicide bombing last week at Baghdad’s bustling commercial area of Karada, killing as many as 300.