Brent crude could jump to around $90 a barrel if the Strait of Hormuz is closed, according to Citigroup Inc., which added that a prolonged halt to shipping through the crucial waterway would be unlikely.

Iran has long asserted that it can shut down the Strait of Hormuz. While the strait can't be "closed" in the traditional sense - like shutting a road - Iran could attempt to make the waterway too dangerous for commercial passage, effectively disrupting global shipping.