Iraqi troops started the final phase of an offensive to recapture Saddam Hussein’s hometown of Tikrit today, a military official said, just hours after the United States launched airstrikes on the Islamic State-held city.

The push, however, is going ahead without the country’s Iran-backed Shiite militias, which had been instrumental to the operation so far and which backed out in a protest over the U.S. action.

A militia spokesman, Mouin al-Kadhimy, said today that many of the Shiite fighters would boycott the Tikrit operation because of the “harmful” involvement of US airstrikes.

Later in the day, clashes intensified as Iraqi troops and special forces moved toward the city center, Lt. Gen. Abdul-Wahab al-Saadi told The Associated Press. Earlier Thursday, an AP reporter heard a second round of airstrikes over Tikrit.

The Islamic State group seized the Sunni city last summer during its lightning advance across northern and western Iraq. The battle for Tikrit is seen as a key step toward eventually driving the Islamic State group from Iraq’s second largest city Mosul, which is further north.

In an address late yesterday, Iraq’s Prime Minister Haider al-Abadi said Iraqi forces began the “final phase” in the Tikrit offensive but did not acknowledge that U.S.-
led coalition forces were playing a direct role. He said Iraqis, “and not anyone but you,” will claim victory against the militant group.

At Iraq’s request, the US began airstrikes on Tikrit on Wednesday in support of the stalled ground offensive, Lt Gen James L Terry, the commander of the US-led campaign to defeat the Islamic State group, said.

He said the airstrikes would “destroy ISIL strongholds with precision, thereby saving innocent Iraqi lives while minimizing” unintended damage to civilian structures. ISIL is one of the acronyms for the Islamic State group.