The greatest risk the oil markets face is that Iran retaliates against Israel airstrikes by closing the Strait of Hormuz, which is critical to global energy shipments.

U.S. oil prices already jumped last week, which could cause prices at the pump to rise about 20 cents a gallon in the coming weeks, according to one estimate.

Asian shares are mixed and oil prices have climbed further as escalating Iran-Israel tensions threaten to disrupt supplies of crude