ISI launch attack

 
ISIS militants have launched an attack on the oil-producing northern Iraqi city of Kirkuk.

There had been recent speculation that ISIS might attack Kirkuk to force Kurdish troops to divert their efforts away from Mosul, ISIS' stronghold in Iraq, about 100 miles to the northwest.

Iraqi Kurdish Peshmerga fighters have moved in around the outskirts of Mosul recently, backed by airstrikes by the U.S.-led international coalition against ISIS,
 

ISIS has been facing off with the Peshmerga -- 

The extremist group has previously held areas on the outskirts of Kirkuk but not the central city.

Kirkuk, in northeast Iraq, is located on top of some of the country's largest oil reserves.

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On Friday, however, ISIS militants took over Maktab Khalid, an area about 12 miles southwest of the city, after heavy clashes with Iraqi Kurdish Peshmerga troops.

Among those killed was Brig. Gen. Shirko Fateh, the highest-ranking operational commander of the Peshmerga brigade located in Kirkuk.

Peshmerga fighters continued to battle, attempting to retake the area.

Hotel stormed

Separately, heavily armed militants attacked an abandoned hotel in central Kirkuk used by local police as headquarters. Police and Peshmerga sources in Kirkuk told CNN that armed men put snipers on the rooftop of the hotel and security forces had surrounded the area.

Peshmerga and Kurdish anti-terror units later raided the hotel, wresting control of it from the militants and killing three of them, Peshmerga sources said. In addition, two suicide bombers detonated themselves in an attempt to keep the Kurdish forces out.

In December, a suicide car bomb attack in Kirkuk that was claimed by ISIS killed at least 17 people and injured more than 20. ISIS said then that it was a message to the Kurdish people and Peshmerga fighters.

Kirkuk is strategically important because of its gigantic oil reserves, almost as large as those in the south of Iraq.

The Kurds and the central Iraqi government in Baghdad have long wrangled over control of those reserves, with each side wanting to keep hold of them. ISIS, which relies heavily on revenue from oil smuggling to fund its operations, has been coveting them too.

Peshmerga forces took over the Kirkuk area in June when the Iraqi army crumbled in the face of ISIS' advances and have played a vital role in defending it from ISIS since.

Peshmerga progress

Despite the latest assault on Kirkuk, Mosul remains the key prize for all sides in Iraq.

The city of 1.5 million people on the Tigris River has been held by ISIS since last June. ISIS has invested heavily in governing the city; its leader Abu Bakr al-Baghdadi pronounced his leadership of the caliphate at the Grand Mosque there last July.

For their part, Kurdish officials say that as long as ISIS holds Mosul, it threatens Kurdistan. Likewise, neither the government in Baghdad nor its coalition partners can rest while terrorists occupy Iraq's second-largest city.

Peshmerga forces have made steady progress against ISIS north and west of Mosul over the past two months.

They have taken some 3,000 square kilometers (1,160 square miles) of the Sinjar area, as well as the area around the Mosul dam, choking off access routes and threatening ISIS' main resupply routes.