TEHRAN, Iran — An Iranian semi-official news agency is reporting that the country's navy has started an exercise in the Caspian Sea.

A Fars story Monday quotes Adm. Khordad Hakimi, chief of the northern naval fleet, as saying that the maneuver in Iran's territorial waters will end Thursday. Hakimi says the exercise is called "Amniat e Paydar" — or "Sustainable Security" in Farsi.

The admiral says that the maneuver is aimed at improving the readiness of Iranian naval forces.

Iran routinely holds land and sea maneuvers, including in the strategic Strait of Hormuz, where ships carrying one fifth of the world's oil supply pass through. Iran, Russia, Azerbaijan, Kazakhstan and Turkmenistan all claim different portions of the Caspian Sea.