President Donald Trump on Saturday said that U.S. and Israeli strikes on Iran killed Ayatollah Ali Khamenei and other top leaders.

“The people that make all the decisions, most of them are gone,” Trump told NBC News in a phone call, adding that “a large amount of leadership” in Iran was also killed, although he declined to go into more detail.

Shortly after the call, Trump posted on Truth Social that Khamenei had been killed in U.S. and Israeli strikes on Iran.

“Khamenei, one of the most evil people in History, is dead,” he wrote. “This is not only Justice for the people of Iran, but for all Great Americans, and those people from many Countries throughout the World, that have been killed or mutilated by Khamenei and his gang of bloodthirsty THUGS.”

Iranian state media appears to have disputed Khamenei’s death, calling an unspecified claim from Trump “baseless,” and said the U.S. president “has a long record of spreading false and fabricated news.” Earlier, Iranian Foreign Minister Abbas Araghachi said Khamenei was alive “as far as I know.”

NBC News asked Trump who will next lead Iran. Trump replied, “I don’t know, but at some point they’ll be calling me to ask who I’d like,” adding that he was “only being a little sarcastic when I say that.”

“But look, it’s going very well. It’s been, you know, we’re, we’re probably in terms of zero to 10. We’re close to the 10 spot, if not there, and it’s thus far been going well, but we have a ways to go. Tremendous damage has been inflicted. The leadership is gone,” he said. “Large, large portions of the leadership.”

The president, who has been monitoring the U.S.-Israel joint operations from his Mar-a-Lago estate in Florida, announced “major combat operations” in Iran in a video statement posted on his Truth Social account early Saturday morning.

“Our objective is to defend the American people by eliminating imminent threats from the Iranian regime, a vicious group of very hard, terrible people. Its menacing activities directly endanger the United States, our troops, our bases overseas and our allies throughout the world,” he said, while also warning that these strikes could result in the deaths or casualties of Americans.

He also urged Iranian citizens to take over their government, saying, “It will be yours to take. This will be probably your only chance for generations.”

The strikes, part of Operation Epic Fury, began at 1:15 a.m. ET, according to U.S. Central Command. “Targets included Islamic Revolutionary Guard Corps command and control facilities, Iranian air defense capabilities, missile and drone launch sites, and military airfields,” CENTCOM said.

The strikes were launched from the air, land and sea, it added, and the U.S. also used “low-cost one-way attack drones for the first time in combat.”

They came after talks over Iran’s missile and nuclear capabilities failed to yield a diplomatic agreement this week.

Most Republican members of Congress lauded the strikes, but Democrats along with Rep. Thomas Massie and Sen. Rand Paul, both Kentucky Republicans, expressed outrage that Trump acted unilaterally without congressional approval. Some of these critical lawmakers said Saturday that they plan to force a war powers vote in the House next week.

When asked by NBC News how he’ll know if the operation is done and was a success, Trump said, “I think it’s already a success. We’ve inflicted tremendous damage. It would take them years to rebuild.”