Iranian armed forced have begun an annual, three-day naval exercise near the strategic Strait of Hormuz, state TV reported.
The report said units from the navy, air force and ground forces were taking part in the drills on September 10 with submarines and drones to be used.
Admiral Habibollah Sayyari, the commander of the annual maneuver dubbed Zolfaghar-99, said on September 9 that the war game was aimed at "improving readiness in confronting foreign threats and any possible invasion."
The Iranian Navy handles all operations in the Gulf of Oman on the eastern side of the Strait of Hormuz, through which 20 percent of all oil traded passes.
In August, the Iranian Navy boarded and briefly detained a Liberian-flagged oil tanker near the Strait of Hormuz.