Brent crude futures climbed to roughly $91 a barrel Monday after Iranian media said an oil tanker had been seized in the Strait of Hormuz. The state-linked Fars News Agency reported on X that a tanker "has been detained," noting that Iran requires shipowners transiting the waterway to pay transit fees. The report, which didn't share the vessel's name or cargo, couldn't immediately be verified.

Oil prices have gyrated wildly during the war based on sometimes-misleading information from Washington and Tehran. But Iran has taken an increasingly hardline approach to the war in recent weeks, including several tankers attempting to pass through the strait.