Iran's state TV is reporting the country's navy has begun maneuvers in the area of the Strait of Hormuz, where one-fifth of the world's oil passes.
It says the maneuvers began early Friday, involving warships, submarines jet fighters and hovercrafts.
The drills come as the West increases its pressure over Iran's nuclear program. The West suspects it may be aimed at producing nuclear weapons, a charge Iran denies.
Iran has threatened to close the straits over Western sanctions but has not repeated the threats lately.
The report says Iran warned ships to stay away from the site until Jan. 3. The maneuvers cover nearly 1 million sq. kilometers (400,000 sq. miles) from the Strait of Hormuz to northern part of Indian Ocean, including the Sea of Oman.