Iraqi and Kurdish officials on Friday welcomed the White House's decision to authorize airstrikes in northern Iraq to counter advancing radical militants. "We thank Barack Obama," said Khalid Jamal Alber, of the Ministry of Religious Affairs for the Kurdish autonomous region of northern Iraq. Iraq's Ministry of the Displaced also welcomed the announcement of air drops of meals and water to refugees trapped on a mountaintop and surrounded by militants.

At least three more towns were taken by militants from the Islamic State of Iraq and al-Sham (ISIS), witnesses told NBC News on Friday. The seizures of Hamdanyah, Bashiqa and Bartella occurred on Wednesday. A string of victories by the ISIS and its allies have sent Iraq's minorities – including thousands of Christians - fleeing for their lives, exacerbating the country's already-dire humanitarian crisis. A senior U.S. defense official told NBC News that "a number of U.S. military aircraft" had successfully delivered food and water and had "safely exited the immediate airspace" around the trapped refugees.

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- Alastair Jamieson

The Associated Press contributed to this report.