Iran's Revolutionary Guards launched naval drills on Wednesday near strategic Gulf islands controlled by Iran but claimed by the United Arab Emirates, state media said.
The manoeuvres, which were being held mainly near Abu Musa island but also around Greater and Lesser Tunb, came two weeks after the United States boosted its naval presence in the Gulf.
It was not immediately clear how long the exercises would last.
"The Islamic Revolutionary Guard Corps naval exercise started Wednesday morning for the defence of the Iranian islands in the Persian Gulf," the official IRNA news agency reported.
It quoted Guards navy commander Ali Ozmaee as saying that the drills "were held in Abu Musa island and Greater and Lesser Tunb".
The three islands -- located near the Strait of Hormuz, the vital sea passage between the Gulf and the open ocean through which a fifth of world oil output passes -- have been a source of contention between the UAE and Iran for decades.
Last month, Iran summoned the Russian ambassador in Tehran to protest a statement by Gulf Arab governments and Moscow, challenging Tehran's claim to the three islands.
IRNA said the Guards naval vessels were equipped with the Ghadir cruise missile system and Fath 360 ballistic missiles.
The Guards had also deployed unmanned surface vessels equipped with artificial intelligence, as well as warplanes, helicopters and aerial drones, the news agency added.
Last month, the US military said it was deploying a destroyer as well as F-35 and F-16 warplanes to the Middle East to deter Iran from seizing ships in the Gulf.
On July 6, the US Navy said the Guards seized a commercial vessel in the Gulf, a day after it accused Iranian forces of two similar attempts off Oman.
Iran later said the seized vessel was carrying "more than one million litres (220,000 gallons) of smuggled fuel".