Story highlights

Iraq stages an offensive against ISIS in Tikrit

ISIS has generally controlled Tikrit since 2014

Irbil, Iraq CNN  — 

Iraqi forces are doubling down efforts to retake the city of Tikrit from ISIS, even uniting Sunni and Shiite fighters in the mission.

The Iraqi army, along with Sunni and Shiite militiamen, attacked ISIS strongholds in the area Monday, the state-run Iraqiya TV reported. Iraqi warplanes and helicopters are also striking targets in and around Tikrit.

It’s part of a wide-scale offensive ordered by Iraqi Prime Minister Haider al-Abadi on Sunday.

Tikrit fell to ISIS in June of 2014, after the group’s capture of Iraq’s second-largest city, Mosul. Tikrit is best known to Westerners as the birthplace of former Iraqi dictator Saddam Hussein.

ISIS, the radical Sunni militant group, has been on a murderous campaign to establish a caliphate across swaths of Iraq and Syria.

Iraqi forces approached Tikrit from several fronts, Iraqiya TV reported, engaging with ISIS north of the city at al-Alam and south of the city at al-Dour.

The element of surprise probably was not a factor, as reports of Iraqi troops amassing near Tikrit were widely shared.

What awaits the Iraqi army is most likely a long, hard slog and not a quick rout. Tikrit is a big city, and the army and its associated militias have had problems recapturing much smaller towns from ISIS.

There have been several failed attempts to recapture Tikrit since the second half of 2014. While Iraqi forces have gained some territory in the area, it has generally been under ISIS control for the last eight months or so.

The joint Iraqi forces fighting to retake Tikrit include Iraqi troops, members of the Shia al-Hashed al-Shaabi militia, members of the Sunni Sons of Salahuddin brigades, and other Sunni tribal fighters.

The offensive involves around 30,000 fighters in all.

Al-Abadi, who is also commander in chief of the armed forces, said on Twitter that he will “oversee the operation to liberate Tikrit” from ISIS.

Why is Tikrit important?

In short, this is the biggest test for an army trying to claw back territory that fell to ISIS last summer after a string of dramatic defeats.

Last June, Tikrit was the scene of the bloodiest massacre ever perpetrated by ISIS militants.

They captured more than a thousand Iraqi soldiers, who laid down their arms and donned civilian clothing in an attempt to flee a base once used by U.S. forces.

ISIS subsequently executed as many as 1,700 soldiers, and posted the video of the killing online.

There is concern that Iraqi forces, eager for revenge, may kill combatants and civilians alike.

The U.N.’s envoy to Iraq, Nickolay Mladenov, urged all armed forces in Tikrit to do their utmost to spare civilians.

What makes this offensive unique?

U.S. and other coalition troops have been conducting a crash course to retrain and upgrade the Iraqi army, and several thousand Iraqi troops have passed through the course.

This offensive will tell whether that training has made a difference.

The offensive also highlights the role played by neighboring Iran in the fight against ISIS.

The semiofficial Iranian FARS news agency reports that Qassim Sulaimani, the commander of the elite Iranian Al-Quds Brigade, is helping oversee the operation to retake Tikrit.

Iran has provided advisers, weapons and ammunition to the Iraqi government.

What’s at stake in Tikrit?

If the offensive succeeds, it means that retaking Mosul, a city 10 times bigger, is possible.

But Tikrit is almost 200 kilometers (124 miles) south of Mosul, and much of the territory in between is under ISIS control.

Al-Abadi has said the immediate goal is to liberate Salah ad-Din province, of which Tikrit is the capital, and then focus on adjacent Al-Anbar province, a similarly Sunni-dominated province. After that, retaking Mosul is an option.

If, however, the Tikrit offensive fails, it could spell disaster for Baghdad.

There will be political recriminations, the already fragile morale of the Iraqi army could collapse, the Kurdish autonomous region could decide to break from Iraq, and it would provide ISIS with a victory it hasn’t seen since last summer.

Ben Wedeman reported from Irbil, and Mariano Castillo reported from Atlanta. CNN’s Yousuf Basil, Holly Yan, Kareem Khadder, Hamdi Alkhshali and Mohammed Tawfeeq contributed to this report.