Military official says no US involvement in strike of senior Hamas leader in Tehran

A U.S. military official tells Fox News the American military had "no involvement" in the assassination of Hamas leader Ismail Haniyeh.

It remains unclear if the U.S. had learned of the operation before Haniyeh died in an airstrike on his residence in Tehran on Wednesday, after attending the inauguration of the country's new president. U.S. Defense Secretary Lloyd Austin could not confirm if Israel was behind the strike nor if military intelligence had warned it would happen.

"I don't have anything for you on that. And we certainly have heard the reporting, but I don't have any additional information," Austin told reporters in Subic Bay, Philippines. He added the U.S. government would seek to ease tensions but that it would come to Israel's defense if the Jewish State is attacked. 

Iran's paramilitary Revolutionary Guard announced Haniyeh's was killed on Wednesday. No one has claimed responsibility for the assassination, but Israel is suspected to be behind it after vowing to eradicate Hamas' senior leaders following the Oct. 7 terror attacks. Hamas invaded southern Israel on that day, killed 1,200 people and took nearly 250 hostages, triggering the war in Gaza.

HAMAS LEADER ISMAIL HANIYEH REPORTEDLY ASSASSINATED

On Tuesday, the Israel Defense Forces announced that they carried out a strike in Beirut, targeting a Hezbollah commander accused of orchestrating a recent attack that killed 12 Israeli children and teens on a soccer field in the Israeli-controlled Golan Heights. Israel and the United States said Hezbollah was responsible, but the terror group denied being behind the attack. 

Israel had promised the attack would not go unanswered. The Israeli strike in Beirut killed Hezbollah's top military commander, Fawad Shah, who U.S. officials say played a role in the killing of 241 American servicemen in the marine barracks bombing in Beirut in 1983. 

"Hezbollah's ongoing aggression and brutal attacks are dragging the people of Lebanon and the entire Middle East into a wider escalation. While we prefer to resolve hostilities without a wider war, the IDF is fully prepared for any scenario," IDF spokesman Rear Admiral Daniel Hagari said. 

Now Haniyeh, the head of Hamas' political bureau, is also dead. While Hamas' Gaza leader Yahya Sinwar is believed to be the mastermind behind the Oct. 7 terror attacks, Haniyeh had lauded them as a humiliating blow to Israel's aura of invincibility.

IRANIAN LEADER KHAMENEI SAYS IT'S A ‘DUTY TO TAKE REVENGE’ AFTER HANIYEH ASSASSINATION

"The Al-Aqsa flood was an earthquake that struck the heart of the Zionist entity and has made major changes at the world level," Haniyeh said in a speech in Iran during the funeral of late Iranian President Ebrahim Raisi in May.

"We will continue the resistance against this enemy until we liberate our land, all our land," Haniyeh said.

In the aftermath of Oct. 7, Haniyeh appeared in a video released by Hamas leading prayers with other top officials in the terror group. They thanked God the tortures, rapes and murders of Israeli men, women and children were successful.

Israel's Heritage Minister Amihai Eliyahu said Haniyeh's death "makes the world a little better." 

"This is the right way to clean the world from this filth," he said in a statement. "No more imaginary ‘peace’ surrender agreements, no more mercy for these mortals. The iron hand that will strike them is the one that will bring peace, and a little comfort, and strengthen our ability to live in peace with those who desire peace." 

HAMAS LEADER HANIYEH ASSASSINATION: FOREIGN GOVERNMENTS CONDEMN ATTACK

Iranian Supreme Leader Ali Khamenei vowed revenge for the assassination in a statement Wednesday.

"The criminal and terrorist Zionist regime martyred our dear guest in our home and made us sad, but it also prepared a harsh punishment for itself," Khamenei said. 

"Martyr Haniyeh was willing to sacrifice his honorable life in this dignified battle for many years. He was prepared for martyrdom and had sacrificed his children and loved ones on this path. He was not afraid of being martyred on the path of God and in order to save the lives of God’s servants. However, following this bitter, tragic event which has taken place within the borders of the Islamic Republic, we believe it is our duty to take revenge."

Haniyeh left the Gaza Strip five years ago and was living in self-imposed exile in Qatar. 

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An Israeli airstrike in April killed three of Haniyeh's sons and four of his grandchildren in Gaza.

More than 39,000 Palestinians have been killed and more than 90,000 wounded in the war in Gaza, according to the Hamas-run Gaza Health Ministry, although the count does not differentiate between civilians and terrorists.

Fox News' Liz Friden and Lucas Tomlinson, Fox News Digital's Landon Mion and The Associated Press contributed to this report.