U.S. Secretary of Defense Lloyd Austin, in the Philippines on Wednesday, was asked about the reported assassination of Hamas leader Ismail Haniyeh in Iran. 

Austin said he’d heard the report but that he did not have any additional information.

Hamas and Iran say Haniyeh, Hamas’s top political leader was killed in an airstrike in Tehran, Hamas and Iran blamed Israel for a shocking assassination that risks escalating the conflict even as the U.S. and other nations were scrambling to prevent an all-out regional war. 

Israel has vowed to kill Haniyeh and other leaders of Hamas over the group’s Oct. 7 attack on Israel that killed 1,200 people. 

The dramatic killing threatened to reverberate on multiple fronts. Hamas could pull out of negotiations for a cease-fire and hostage-release deal in the 10-month-old war in Gaza, which U.S. mediators had said were making progress. 

And the killing could enflame already heightening tensions between Israel and Iran’s powerful Lebanese ally Hezbollah.