Defense Secretary Pete Hegseth and Joint Chiefs of Staff Chairman Gen. Dan Caine declined to definitively say on Wednesday whether they believed Iran would use a nuclear weapon if it acquired one. 

As they testified before the Senate Appropriations defense subcommittee, Sen. Lindsey Graham (R-SC) asked Hegseth and Caine to provide their “professional military judgement” on whether they agreed with Israel’s assessment that Tehran would use a nuclear weapon against the Jewish state. 

“I think they would potentially do that,” Caine said. “I think they’d use it to pressure Israel. I don’t know whether they would use it.”

“I think Israel believes, and quite understandably, that it is an existential threat to their existence, and that in the hands of the wrong Iranian, a cleric or a radical, that they would seek to use it,” Hegseth said. 

Graham replied to Hegseth, “Well, is this a radical cleric that exists there today? If he’s not, who the hell would be? So I’m trying to get everybody to think, let’s don’t do what we did in the ‘30s. They’re going to use a nuclear weapon if they get it.”

The South Carolina senator began his questioning on the topic by asking Hegseth and Caine if each thought the world “miscalculated Hitler in the ‘20s and ’30s,” which both men responded to affirmatively. “We certainly did not understand the scope of the threat, yes,” Hegseth replied. 

“The guy wrote a book [saying that] I want to kill all the Jews and nobody believed him. … The danger of that is like 50 million people get killed. So let’s not do that now,” Graham said.

After asking Hegseth and Caine about the Iranian nuclear program, Graham pressed both about China’s intentions in Taiwan and Russia’s plans in Europe beyond Ukraine while encouraging them to take a tougher posture on U.S. adversaries. 

“Listen, I like what you’re doing. I just think we got to get this stuff right. Iran cannot have a nuclear weapon because they’ll use it. They’re homicidal maniacs who are religious Nazis. China is an expansionist power who will take Taiwan if we don’t deter them. Russia will dismember Ukraine and keep going if we don’t stop them,” Graham told the two. 

Graham then turned to the issue of radical Islamic terrorism and asked if al-Qaida would use a nuclear weapon if it acquired one. “A nuclear weapon in the hands of al-Qaida would be a very bad thing,” Hegseth replied.

“Is there a whole lot of difference between a nuclear weapon in the hands of al-Qaida and the Ayatollah in Iran? I don’t think so. They just have a different religious reason to do it,” Graham said. 

At a Senate hearing, @LindseyGrahamSC asked Defense Secretary Pete Hegseth and Joint Chiefs of Staff Chairman Gen. Dan Caine whether they believed Iran would use a nuclear weapon if it acquired one.

"I’m trying to get everybody to think, let’s don’t do what we did in the ‘30s.… pic.twitter.com/e6U7nIKwPS

— Jewish Insider (@J_Insider) June 11, 2025

Graham is set to introduce a resolution on Thursday affirming that the only acceptable outcome of U.S. nuclear talks with Iran would be the total dismantlement of its enrichment program.

Many Republicans on Capitol Hill have expressed concern that the Trump administration could agree to a deal with terms similar to former President Barack Obama’s 2015 nuclear agreement. 

For his part, Graham has expressed confidence that Trump would not allow for any enrichment, citing recent private conversations with the president.