American C-130 aircraft carried out an airdrop of food near Al-Asad air base early on Monday at the request of the Baghdad government, Pentagon spokesman Rear Admiral John Kirby told reporters.
US aircraft delivered more than 7,000 Halal meals that were retrieved by Iraqi forces and then delivered to the Albu Nimr tribe, which had been forced to flee homes near Heet due to Islamic State (IS) group's "aggression," Kirby said.
"This assistance is just another example of our resolve to assist the people of Iraq and deny ISIL (IS) key terrain and safe haven, as well as our commitment to assist those forces who are opposing" the group, he said.
The tribe numbered in the thousands, defense officials said.
Ferrying in humanitarian aid by air to Anbar province underscored the Iraqi government's difficulties in the west and suggested Baghdad troops were not able to move safely over roads in the area.
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The IS militants have been pushing back Iraqi forces in the west over the past month and Iraqi army troops stationed on the edge of Heet were forced to withdraw earlier this month and fall back to the Asad base.
Surrounded by desert, Asad is a large base northwest of Heet and one of the last still under government control in the restive province.
The Pentagon said Iraqi troops and Kurdish forces had made gains elsewhere in Iraq over that past 36 hours.
In central Iraq, north of Baghad, Iraqi troops had expanded control of territory near the Baiji oil refinery and were "making progress," Kirby said.
The Iraqi forces also had advanced against the IS militants west of Baghdad, said Kirby, without providing more details.
In northern Iraq, Kirby touted a counter-attack in which Kurdish Peshmerga forces retook the town of Zumar from the IS jihadists, saying it was the latest in a string of successful operations by the Kurds.
Kurdish commanders on Saturday said their troops had captured the town.