Republican Rep. Thomas Massie took to the House floor Monday to call for an investigation into Israel’s 1967 attack on an American spy ship, giving new prominence to a decades-old conspiracy theory that has become a touchstone for critics of Israel.

“It’s my great honor, maybe one of the biggest honors of my lifetime, to stand here on the floor and do something that’s 59 years overdue, to recognize the survivors and those who gave their lives on the USS Liberty,” Massie said. “Fifty-nine years ago today, when they were viciously attacked by IDF jets and also after that by torpedo boats.”

The attack on the USS Liberty occurred on June 8, 1967, in the midst of Israel’s Six-Day War. The intelligence-gathering ship was stationed off the shore of the Sinai Peninsula during the conflict when it came under attack by Israeli forces, killing 34 crew members and injuring 171 more.

Israel later apologized for the attack, explaining it had mistaken the boat for Egyptian, and paid damages to the US and the families of the victims. Multiple US investigations, including by the CIA, have since determined that the attack was a mistake.

Still, the incident has become a rallying point for critics of Israel who claim the attack was deliberate and gained more adherents lately as anti-Israel sentiment has swelled. On Friday, Massie cited a host of US military and intelligence officials he said had cast doubt on the outcomes of the US investigations.

“None of these distinguished men think this was an accident,” Massie continued. “They think it was intentional murder by the country of Israel, either as a false flag operation or because they simply didn’t want anybody observing what they were doing that day.”

Massie, who will be departing Congress next year after losing his primary in Kentucky, used the anniversary of the incident to call for Congress to pass a resolution honoring the victims of the attack and for a new investigation into the circumstances surrounding it.

The USS Liberty Veterans Association praised Massie’s remarks in a post on X/Twitter, writing that it was a story that “NO other member of Congress will even listen to.”

Massie is far from the only critic of Israel to use the attack as broader evidence of Israeli misconduct.

Last year, the far-right influencer Candace Owens interviewed a survivor of the attack and tweeted that there was “perhaps no story that can more enlighten you to the deceitful and despicable nature of the modern state of Israel — and its stranglehold on the American government.”

Florida gubernatorial candidate James Fishback has called for the attack to be taught in schools, and the antisemitic streamer Nick Fuentes has claimed that Israel initiated the attack to “conceal their troop movements.”

During his speech at Amfest in December, conservative pundit Tucker Carlson, who devoted part of his podcast last year to elevating the conspiracy theory that the attack was a false flag operation on the part of Israel, told attendees that asking “why a foreign government tried to sink one of our ships in 1967” does not “make you an antisemite.”

Oren Segal, the ADL’s vice president of counterextremism and intelligence, told the Jewish Telegraphic Agency that his organization had been concerned about the “normalization” of Carlson’s views, including his rhetoric on the USS Liberty attack.

“No one’s been a bigger boon to the USS Liberty conspiracy of late than Tucker Carlson,” Segal said.

Following Carlson’s remarks at Amfest, the annual conference of the right-wing group Turning Point USA, the ADL denounced conspiracy theories about the attack that it said had swirled for decades.

“Despite official findings that the attack was a tragic case of mistaken identity, these narratives continue to be amplified by actors seeking to inflame distrust and undermine US-Israel relations,” the ADL said in a post on X.

At the conference, the Jewish pundit Ben Shapiro was also asked about the attack by an audience member, and responded that “the vast majority of people who bring this up are doing so to suggest that Israel deliberately attacked an American ship because Israel deliberately wants to harm America.”

Some of Massie’s fellow critics of Israel praised him for bringing up the incident on the floor of Congress on Monday.

“Thank you Thomas Massie for recognizing the heroic members of the USS Liberty, which was attacked by Israel, where 34 crew members were killed and 174 were wounded,” tweeted Marjorie Taylor Greene, the former member of Congress. “Why did our ‘greatest ally’ attack us??”

Other right-wing figures, including at least one member of Congress, criticized Massie’s gambit.

Rep. Dan Crenshaw of Texas tweeted that he had previously believed that Massie was “standing on heartfelt principles and had intellectual backing,” even as they did not always agree.

“But comments like this make me question his authenticity,” Crenshaw wrote. “The USS Liberty incident is a tragic one, but it’s an incident with a clear conclusion if one uses any objective analysis of the facts. … Perhaps we are simply witnessing another example of the irresistible incentive to jump on the bandwagon of grifters that guarantee you a specific kind of social media audience and attention that ultimately results in profits.”

Adam Mossoff, a former legal fellow of the right-wing Heritage Foundation, took aim at Massie’s address in a post on X, writing that the Kentucky Republican had “fully gone down the rabbit hole of antisemitism and Jewish conspiracy theories — via the modern American antisemite’s favorite boogeyman, Israel.”

“For the American woke left and woke right, the USS Liberty is the equivalent of the Dreyfuss Affair in France,” Mossoff wrote. “It’s the cause celebres of nationalism and bigotry in which history’s greatest villains — the Jews — can be smeared again with nefarious and evil motives.”