The U.S. and its allies will use the newly recaptured Iraqi air base in Qayyarah as headquarters in the mission to liberate Mosul city from the Islamic State group, U.S. Defense Secretary Ashton Carter announced Monday when he arrived in Baghdad on an unannounced visit.

The Pentagon chief is set to discuss the Iraqi army’s plan in recapturing Mosul and U.S. involvement in the mission. The Islamic State group, also known as ISIS, has been holding Mosul, the largest Iraqi city under the Sunni militant group's control, since June 2014. Iraqi Prime Minister Haider al-Abadi announced Saturday that Iraqi forces backed by U.S.-led airstrikes retook Qayyarah near Mosul, CNN reported.

“Iraqi Security Forces, accompanied and advised by us as needed, will complete the southern-most envelopment of Mosul. That's its strategic role, and that's its strategic importance,” Carter said at a press conference in Baghdad.

The U.S. defense secretary described the recapture of Qayyarah as a key strategic victory. “The point of seizing that [Qayyarah] airfield is to be able to establish a logistics and air hub in the immediate vicinity of Mosul,” Carter said. “So, there will be U.S. logistics support.”

Carter will meet the Iraqi prime minister and Minister of Defense Khalid al-Obeidi during the visit. Carter was greeted by Lt. Gen. Sean MacFarland, the top U.S. military commander for the fight against ISIS, and Stuart Jones, the U.S. ambassador to Iraq, when he landed in Baghdad.

Mosul native Obeidi reportedly said that “2016 will be the year of the liberation of Mosul and the rest of Iraq.” In just over a year, Iraq has managed to drive the ISIS out of important cities of Tikrit, Ramadi and Fallujah.

Washington will deploy around 200 additional troops mostly as advisors for Iraqi troops to help Iraq in their Mosul mission, U.S. defense officials said Monday, according to a Reuters report.

In an interview with CBS News, U.S. President Barack Obama said, “As we see the Iraqis willing to fight and gaining ground, let's make sure that we are providing them more support. My expectation is that by the end of the year, we will have created the conditions whereby Mosul will eventually fall.”