TEL AVIV, Israel — The U.S. military struck three sites in Iran early Sunday, inserting itself into Israel ’s war aimed at destroying the country’s nuclear program in a risky gambit to weaken a longtime foe amid Tehran’s threat of reprisals that could spark a wider regional conflict.

President Trump has said there is little he could do to stop the Israeli attacks. A European diplomatic effort to rein in the hostilities ended without a breakthrough on Friday.

Israel’s air force launched a series of strikes targeting missile storage and launch infrastructure in central Iran, the Israeli military said. Tehran also launched a barrage of missiles toward central Israel.