Oil prices surged 2.6 percent and U.S. stock futures fell after American airstrikes over the weekend targeted three Iranian nuclear facilities.

A U.S. official said that six American warplanes dropped a dozen 30,000-pound bunker-busters on the Fordo nuclear site, and that Navy submarines fired 30 cruise missiles at the Natanz and Isfahan sites. One B-2 bomber also dropped two bunker-busters on Natanz, the official said.