The U.S. military said on Tuesday that it was striking military targets in Iran in retaliation for Iranian attacks on ships and U.S. forces in the region, raising the risk of a renewed round of fighting.

U.S. Central Command did not specify where it was striking in Iran, but it said the attacks were targeting Iran’s Islamic Revolutionary Guards Corps. Iranian state media said projectiles had hit sites in Chabahar and Konarak, two southern port cities east of the Strait of Hormuz.

The new round of U.S. strikes comes after the two countries exchanged attacks on Sunday, puncturing a monthlong calm since Mr. Trump pulled back after concerns over dwindling U.S. munition stockpiles. The hostilities underscore that the conflict, which began six months ago, appears far from a durable solution.

The U.S. military said on Sunday that its forces had bombarded Iranian troops on Larak Island that were preparing to launch rockets armed with mines into the Strait of Hormuz, the vital shipping corridor for oil and gas. The Iranian foreign ministry said several people were killed and wounded but did not provide specifics.

The Islamic Revolutionary Guards Corps said it retaliated by firing at bases in Jordan and the United Arab Emirates that host U.S. military personnel. The Jordanian authorities said that they had intercepted eight missiles in their airspace, while the Emirati military said it had “responded to” a drone from Iran. There were no reports of damage or casualties.

This is a developing story. Check back for updates.