Oil prices climbed on Monday, extending Friday's rally, as renewed strikes by Israel and Iran over the weekend increased concerns that the battle could widen across the region and significantly disrupt oil exports from the Middle East.

Crude oil futures jumped more than 3% Sunday after Israel struck two natural gas facilities in Iran, raising fears that the war will expand to energy infrastructure and disrupt supplies in the region.

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.

Iran and Israel continued on Sunday their aerial attacks, which began Friday with a series of Israeli strikes on Iran.

Open hostilities between Israel and Iran entered a fourth day on Monday with no sign of easing, stoking fears of a wider war in the oil-rich region.

Israel’s attack on Iranian nuclear and military sites on Friday, and the resulting oil-price surge and airline-stock slump, could pose even more obstacles for consumers navigating an already unusual summer travel season.