Iran's Revolutionary Guards began naval exercises Wednesday in the Strait of Hormuz, just a few hundred kilometres away from western vessels engaged in the fight against the Islamic State group.
The three branches of the elite army of the Iranian regime are participating in the regular military exercises, dubbed "Great Prophet", off Qeshm Island.
It was unclear how long the drills would last.
State television showed an attack by "high-precision missiles" fired from the coast, and a helicopter on a replica of an "American" aircraft carrier.
Fast attack craft were also involved in the military exercises, which aim to "demonstrate the power" of the Navy in protecting Iranian interests in the Gulf, according to state television.
The Revolutionary Guards are responsible for naval forces in the Gulf, mainly composed of hundreds of speedboats equipped with various types of short- and medium-range missiles as well as small submarines.
The Guards' naval forces, estimated at about 20,000 troops by Western experts, are tasked with blocking the Strait of Hormuz, through which a third of global marine oil traffic passes, if the country comes under attack.
Iran says its military doctrine is based entirely on deterrence.
The exercises began two days after French aircraft carrier Charles de Gaulle launched operations in the Gulf as part of the international coalition fighting the Islamic State group (IS) in Iraq and Syria.
The ship will be stationed off Saudi Arabia for about eight weeks, working alongside the American aircraft carrier USS Carl Vinson.
The US Fifth Fleet is stationed in Bahrain, and Qatar hosts the US military command for the Middle East and Central Asia.
A nuclear-powered attack submarine, a French anti-aircraft frigate and a British anti-submarine frigate are also in the area.