President Donald Trump says the U.S. military struck three sites in Iran, directly joining Israel’s effort to decapitate 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.

The decision to directly involve the U.S. comes after more than a week of strikes by Israel on Iran that have moved 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 a 30,000-lb. 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.

Iran’s state-run IRNA news agency early Sunday acknowledged an attack on the country’s Fordo nuclear site.

The Associated Press is providing a livestream of Trump’s 10 p.m. ET address to the nation. Watch below: