Urging Iranians to overthrow their clerical rulers, the US launched "major combat operations" along with Israel against Iran early on Saturday.
The US is calling the operation "Epic Fury", while the Israelis call it "Lion's Roar".
US President Donald Trump said Iran's Supreme Leader Ali Khamenei had been killed.
It came two days after US-Iranian talks on Tehran's nuclear programme ended without a deal.
Iran launched counter-attacks throughout the Middle East in retaliation to what its foreign minister called an "unprovoked, illegal" attack by the US and Israel.
