The Iranian navy gave nearby traffic only 23 minutes before shooting unguided rockets near ships
The Iranian navy test fired several rockets near a US aircraft carrier and two other vessels last week, a US military official said on Tuesday.
Though the rockets were not fired toward any ship, their proximity to the warships - and several commercial vessels - has sparked concern.
"We look at this firing so close to the ships as highly provocative," said the military official, who was not immediately authorised to be named.
The official confirmed details of an NBC News report that said one rocket came within about 1,500 metres of the USS Truman as it transited the Strait of Hormuz on 26 December.
A French frigate and the USS Bulkeley destroyer were also in the area.
Nearby traffic was given only 23 minutes advanced warning that the Iranians were preparing to shoot rockets, Navy Commander Kyle Raines, spokesman for US Central Command, told Reuters.
The official said the unguided rockets were fired from an Iranian navy "fast inshore attack craft" that was in Omani waters.
The Western vessels did not need to take evasive action, the official said.