Iran’s elite Revolutionary Guards began three days of large-scale war games in the Gulf and Strait of Hormuz on Thursday, state television reported.

The military manoeuvres, in a waterway crucial for global crude supplies, coincided with rising tension between Iran and the West, which fears Tehran’s nuclear programme is aimed at developing bombs. Iran denies the charge.

On Wednesday, the Pentagon said U.S. military action against Iran remained an option even as Washington pursues diplomacy and sanctions to halt the Islamic Republic’s atomic activities.

Iran’s armed forces often hold drills in an apparent bid to show their readiness to deter any military action by Israel or the United States, its arch foes.

State Press TV said Iran had begun the exercise in the Gulf and the Strait of Hormuz “to show off its defensive capabilities and its determination to maintain security” in the region.

The Guards’ naval, air and ground forces were taking part in the “major drill that seeks to display Iran’s constructive and determined military power in establishing security in the strategic region”, the English-language station said.

It said new weapon systems would be demonstrated during the exercise, but gave no details.

The United States is pushing for a fourth round of U.N. sanctions on Tehran over its refusal to halt sensitive nuclear activities as demanded by the U.N. Security Council, including proposed moves against members of the Guards.

Israel, widely believed to have the Middle East’s only atomic arsenal, has described Iran’s nuclear programme as a threat to its existence. Although it says it wants a diplomatic solution, Washington also has not ruled out military action.

Iran, a predominantly Shi’ite Muslim state, has said it would respond to any attack by targeting U.S. interests in the region and Israel, as well as closing the Strait of Hormuz.

About 40 percent of the world’s traded oil leaves the Gulf region through the strategic narrows.

(Writing by Fredrik Dahl; editing by Michael Roddy)