He is the son of assassinated Supreme Leader Ayatollah Ali Khamenei.
President Donald Trump announced "major combat operations" against Iran on Feb. 28, with massive joint U.S.-Israel strikes attack targeting military and government sites, officials said.
Iranian state television confirmed that Ayatollah Ali Khamenei was among those killed by airstrikes in Tehran on the first day of strikes. His successor is yet to be named.
Iran is responding to the operation with missile and drone attacks targeting Israel, regional U.S. bases and multiple Gulf nations. Israel is also intensifying its long-running strike campaign against the Iran-backed Hezbollah militia in Lebanon.
(Read previous Iran live updates here.)
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Islamic Revolutionary Guard Corps Brigadier General Mohammad Akraminia said Iran has prepared for a "long-term war," according to state media.
"Today we can continue to fight for as long as the country's authorities want," he said, according to state media.
The House voted Thursday to reopen the Department of Homeland Security -- as Republicans continue to call on Democrats to end the ongoing partial shutdown amid ongoing hostilities in Iran and a heightened threat level in the United States.
By a vote of 221-209, the measure prevailed in the lower chamber. Four Democrats -- Reps. Henry Cuellar, Jared Golden, Donald Davis and Marie Gluesenkamp Perez -- voted with the united GOP majority.
The measure heads back to the Senate, where 60 votes are needed to overcome Democratic opposition to the funding, which lapsed on Feb. 14.
"Despite bipartisan majorities in both chambers, Senate Democrats continue to hold this funding hostage," House Appropriations Chairman Tom Cole stated after Thursday's vote. "Shielding the homeland should never be treated as a political bargaining chip."
-ABC News' John Parkinson
The State Department advised U.S. government personnel not to travel to Azerbaijan's Nakhchivan region in a new security alert issued Thursday.
The alert comes after Azerbaijan's Foreign Ministry said earlier Thursday that drones struck the city of Nakhchivan, just north of the country's border with Iran. One drone hit the city's airport, the ministry said.
House Speaker Mike Johnson continued to argue that the U.S. is not at war with Iran, following the failed war powers resolution vote in the House on Thursday.
"We are not at war. We have no intention of being at war," he told reporters. "The Department of War has made it very clear -- this is a limited operation. It's an operation that is limited in its scope and duration."
Johnson's comments come a day after President Donald Trump said: "I have to go back and look at the war. You know, I have a lot of things happening.”
The House speaker said he is "grateful" that the resolution failed.
"It would have been a very dangerous gambit to take the commander-in-chief's ability away to complete this mission. Would have been a very serious misstep by Congress," Johnson said.
-ABC News' Lauren Peller
