A U.S. official says intelligence information that prompted the Pentagon to send an aircraft carrier and Air Force bombers to the Middle East included indications that Iran had moved short-range ballistic missiles aboard boats in or near the Persian Gulf.

The official spoke on condition of anonymity in order to discuss sensitive information.

The official says the movement of missiles was among a wider range of troubling intelligence information that led to the decision announced Sunday to speed up the deployment of the USS Abraham Lincoln carrier strike group from the Mediterranean Sea to the Middle East.

At the Pentagon, Acting Defense Secretary Patrick Shanahan told reporters the U.S. was being "very prudent and very measured" in its approach to perceived Iranian threats.