Iraq 'retakes 25% of Islamic State territory'
Islamic State (IS) has lost more than a quarter of its territory in Iraq since US-led coalition air strikes began in August, the Pentagon has said.
That equated to 12,950 to 15,540 sq km (5,000 to 6,000 sq miles), spokesman Col Steve Warren told reporters.
The combination of air power and Iraqi ground forces was affecting the group's ability to hold territory, he said.
The announcement came ahead of a meeting between Iraq's prime minister and Barack Obama in Washington.
Before leaving for the US, Haider al-Abadi made clear that he wanted the coalition to step up its air campaign against IS, which seized large swathes of Iraq last June after routing the Iraqi army.
He is also expected to press Obama for billions of dollars of advanced US weaponry, including attack helicopters and surveillance drones.
While Col Warren told reporters in Washington on Thursday that IS had lost 25%-30% of territory.
He said that while it was too early to say the tide of the battle was turning in Iraq, coalition and government forces had "unquestionably inflicted some damage on [IS] and have pushed [IS] back in a somewhat meaningful way".
A Pentagon map showed the jihadist group had "lost large areas where it was once dominant" and the frontline had been pushed either west or south, depending on location, in the provinces of Irbil, Babil, Baghdad and Kirkuk, Col Warren said.
"Among other strategic infrastructure and sizeable towns where [IS] has lost territory are Mosul Dam, Zummar and the vicinity of Sinjar Mountain."
The corridor north of Tikrit had been "substantially retaken by friendly forces" and the city was expected to be cleared of militants "relatively soon", he said.
The town of Baiji and the nearby oil refinery, Iraq's most important, is still contested, and will continue to be the focus of air strikes.
Abadi also announced last week the launch of a new offensive to drive IS out of the country's biggest province, Anbar, west of Baghdad. However, IS responded by overrunning two districts on the outskirts of the provincial capital, Ramadi.
The Pentagon said Islamic State's area of influence in neighbouring Syria, where coalition air strikes began in September, remained largely unchanged, with its gains in Suweida, Damascus Countryside and Homs provinces offset by losses in the provinces of Aleppo and Hassakeh.