Press secretary Rear Admiral John Kirby confirmed "armed and manned" US aircraft would fly from Arbil, capital of Iraq's autonomous Kurdish region, but declined to provide more details.
American fighter jets and other warplanes bombing IS militants in Iraq previously have been flying out of bases and from aircraft carriers in the region outside Iraq.
The airfield in Arbil would allow some fighter jets easier access to the battlefront, a defense official told AFP, speaking on condition of anonymity.
The use of Arbil's air base reflects the broadening US campaign against IS militants, though attack helicopters already have been flying out of bases in Iraq.
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The Pentagon did not say what type of "manned" aircraft were involved or how many aircraft will deploy to Arbil.
"There's still some decisions that have yet to be made on exact sourcing solutions," Kirby told reporters.
But he indicated that US bombing raids in Iraq would expand in support of Iraqi government and Kurdish forces battling the IS militants.
His comments came a day after President Barack Obama's vow to wage a "relentless" war against the IS extremists in Iraq and Syria, under a plan that relies on US air power while arming and training local forces battling the jihadists.
Since August 8, US aircraft have carried out more than 150 bombing raids in Iraq, with most of the strikes targeting IS militants threatening Mosul dam.
Obama's strategy calls for more more assistance for local forces in Iraq and "moderate" rebel fighters in Syria, with an additional 475 troops to serve as "advisers" to Iraqi troops or in support roles.