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.

Oil futures jumped as the market reopened Sunday night, building on last week’s surge after Israel attacked Iranian energy facilities over the weekend and underlining fears around potential disruption to Middle Eastern crude flows.