President Donald Trump speaks at the National Prayer breakfast in Washington, D.C., on Thursday. (The Center Square)

The U.S. military struck three sites in Iran early Sunday, directly joining Israel ’s war aimed at decapitating 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.

Addressing the nation from the White House, President Donald Trump said Iran’s key nuclear sites were “completely and fully obliterated.” He also warned Tehran against carrying out retaliatory attacks against the U.S., saying Iran has a choice between “peace or tragedy.”

Iran’s nuclear agency confirmed that attacks hit its Fordo, Isfahan and Natanz atomic sites, but insisted that its work will not be stopped.

The decision to directly involve the U.S. in the war comes after more than a week of strikes by Israel on Iran that aimed to systematically eradicate the country’s air defenses and offensive missile capabilities, while damaging its nuclear enrichment facilities. But U.S. and Israeli officials have said that American stealth bombers and the 30,000-pound bunker buster bomb they alone can carry offered the best chance of destroying heavily fortified sites connected to the Iranian nuclear program buried deep underground.

“We have completed our very successful attack on the three Nuclear sites in Iran, including Fordow, Natanz, and Esfahan,” Trump said in a post on social media. “All planes are now outside of Iran air space. A full payload of BOMBS was dropped on the primary site, Fordow. All planes are safely on their way home.”