Troops at the Iraqi air base that bore the brunt of Iran's first direct missile attack against U.S. forces said they were shocked by its intensity and grateful to emerge unscathed.

The scale of the damage at the Ain al-Asad base showed Iran's destructive capability at a time when U.S. officials say they are still concerned that Iran-backed groups across the region could wage attacks on the United States.

"It's miraculous no one was hurt," Lt. Col. Staci Coleman, the U.S. air force officer who runs the airfield, told reporters on Monday at the vast base deep in the western Anbar desert in Iraq, where 1,500 Americans were deployed.