Iran live updates: Israeli officials say Iranian Supreme Leader Ali Khamenei believed dead in strikes

(ABC NEWS) -- President Donald Trump announced "major combat operations" against Iran on Saturday, with daytime strikes in the joint U.S.-Israel attack targeting military and government sites, officials said.

The massive operation sparked threats of retaliation by Iran and reports of incoming missiles and drones around the region.

"Our objective is to defend the American people by eliminating imminent threats from the Iranian regime, a vicious group of very hard, terrible people," Trump said in a video statement.

U.S. officials said the operation could potentially last days, and Trump acknowledged that there may be American casualties.

Iran's Supreme Leader Ayatollah Ali Khamenei and President Masoud Pezeshkian were both targeted in the U.S.-Israeli attack, according to three sources briefed.

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