India, July 24 -- Bahrain activated its sirens early Friday, warning residents to shelter from detected fire hours after the U.S. military said it had wrapped up its 13th night of strikes against Iran.

The Gulf states have come under frequent fire over the past week as the U.S. and Iran exchange escalating strikes in fighting that began with a struggle over control of the strategic Strait of Hormuz.

The previous day, Yemen's Iran-backed Houthi rebels said they targeted two Saudi oil tankers in the Red Sea, potentially widening the Iran war as international oil topped $100 a barrel.

Blasts were also reported Thursday on Iran's Qeshm Island, home to stores of naval assets including drone boats that Iran can use to attack vessels on the S...