Iraqi forces fighting the terror group ISIS in its last stronghold in Iraq, Mosul, have reached the Nineveh province governance building and raised the Iraqi flag there, a senior U.S. defense official said on Friday.

Reuters reported that Iraqi forces retook most districts in eastern Mosul during nearly three months of a U.S.-backed offensive, which accelerated at the turn of the year with new tactics and better coordination.

“It is both a symbolic victory and a significant operational victory,” Elissa Slotkin, the acting assistant secretary of defense for international security affairs, said during a Pentagon briefing.

Slotkin also said that a liaison team was in talks with Turkey about helping its forces near al-Bab in Syria and has already provided surveillance support.

“We have provided some ISR (Intelligence, Surveillance, Reconnaissance) support in al-Bab… those are the kinds of things that we are talking about, sort off on an hourly bases with the Turks,” she said.

Earlier this month, the Pentagon said the U.S.-led coalition had carried out flights in support of Turkish forces near the ISIS-controlled town of al-Bab but did not carry out air strikes.

The U.S.-led coalition has been reluctant to provide support to NATO member Turkey for its advance towards al-Bab. Turkey recently called on the coalition to provide air support for Turkish-backed troops besieging the town.