An Iranian navy commander said in October that Iran had begun building a series of bases along its southern coast on the Sea of Oman and up to the Strait of Hormuz, at the entrance to the Gulf, to improve its defensive capabilities.
"Not that I'm aware of," vice-admiral William Gortney, commander of the U.S. Navy's Fifth Fleet, told Reuters on the sidelines of a conference in Manama, when asked whether he had any evidence that construction had begun.
"I (only) know that they stated the intention," he said.
A build-up of naval power could make it easier for Iran to close the Strait of Hormuz, a narrow sea lane through which some 40 percent of traded oil is shipped.
A top military adviser to Iran's Supreme Leader Ayatollah Ali Khamenei was also quoted last year as saying the elite Revolutionary Guards would take command of Gulf defense.
Gortney said he expected the realignment of the command structure to take time, without elaborating.
He said the change in command on the Iranian side had not had any negative impact on radio communications between U.S. and Iranian navy ships to coordinate passage through the Strait of Hormuz.
"We communicate only bridge-to-bridge and we continue to do that," he said.
Tension has risen in the region because of Iran's nuclear energy program, which the West, Israel and many Arab states suspect is a cover for developing atomic weapons. Iran denies having nuclear weapons ambitions.
(Reporting by Frederik Richter; Editing by Mark Trevelyan)
