Iran's Revolutionary Guards have carried out missile tests as they begin three days of war games.
Iran's state media say the exercise, which began Monday, covers 16 of Iran's 30 provinces, and involves 20 brigades of the elite guards - an independent wing of Iran's armed forces, controlled directly by the country's supreme leader Ayatollah Ali Khamenei.
Two weeks ago, Iran conducted two days of war games and tested new Russian-built air defenses.
Iran says the exercises are to improve its defense capabilities.
Tensions between Iran and the United States have been increasing recently. Washington says Tehran is meddling in Iraq.
The U.S. and other Western nations also accuse Tehran of seeking nuclear weapons. Iran denies the accusation.
The United States has sent aircraft carriers to the Persian Gulf, but says there are no plans to go to war with Iran.
Some information for this report was provided by AFP, AP and Reuters.