A top US general says "defensive measures" prevented deaths when Iranian missiles hit two military bases in Iraq.
Ballistic missiles were fired at installations housing British and American troops - Al-Asad air base and a site in Erbil.
No casualties among coaltion forces were reported.
Chairman of the US Joint Chiefs of Staff, General Mark Milley said: "There's sirens that go off on these bases...There's bunkers and jersey barriers, and there's places to go hide and all that.
"We have various levels of protective gear, and we have various scatter plans that do certain things," he added.
Gen Milley said despite no loss of life, he believes the Iranians intended to kill.
"The points of impact were close enough to personnel and equipment ... that I believe, based on what I saw and what I know, is that they were intended to cause structural damage, destroy vehicles and equipment and aircraft, and to kill personnel," Gen Milley said.
"That's my own personal assessment."
US Secretary of Defense Mark Esper said he is cautious about drawing any conclusions that if the Iranians did intend to cause death, they would attempt it again.
"We are not going to do anything imprudent," Mr Esper said.
"These are serious times, and we take things one step at a time."
General Milley and Mr Esper say intelligence analysts are reviewing the attacks and preparing a final assessment.
Cover image: Al-Asad air base is used by British and American forces (Picture: US Department of Defense).