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.

Asian shares were mixed on Monday and oil prices extended gains on worries that escalating Iran-Israel tensions could disrupt the flow of crude around the world. U.S. benchmark crude oil added 20 cents to $73.

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.