Joseph Gordon-Levitt and Sophia Bush are among the Hollywood actors jumping to defend their involvement with billionaire investor Peter Thiel‘s mysterious Dialog group, assuring fans that they do not know the controversial conservative political activist and that the meetings are not “a single ideological gathering.”

The stars, including Josh Brolin, are responding to a list of attendees leaked to The Hollywood Reporter and published this week, revealing to the public their affiliation with the private and invite-only group that is linked to Thiel, the co-founder of data analytics firm Palantir Technologies and the man apparently behind the group, which invites powerbrokers across the world in politics, tech and media to discuss “off-the-record ideas” in privacy.

Researcher Maia Arson Crimes provided THR with materials about the group, including a membership directory and details about this year’s upcoming forum. Brolin, Gordon-Levitt, Bush, Scooter Braun, Isaac Lee, A24’s Scott Belsky, composer-producer Benj Pasek, CEO of The Atlantic Nick Thompson and Ezra Klein of The New York Times were among the famous names in the directory. It also includes Trump administration officials, two senators, six members of the so-called PayPal Mafia, a current ambassador to the United States, and several billionaires, including Elon Musk.

Scrutiny of Dialog and those named on the leaked list has been growing, as questions swirl about how and why these Hollywood actors were invited to the secretive conferences and why they are rubbing elbows with several individuals with opposing perspectives to discuss important, hot-button issues in the shadows.

“I understand why people have questions and are suspicious,” Gordon-Levitt wrote in a statement on his personal Instagram. “Some of the headlines and posts circulating about this are alarming, if not bizarre. So let me clarify: I have been to two Dialog conferences. But, I do not know Peter Thiel. I’ve never met him. I’ve never spoken with him or his representatives. I’ve never seen him at an event. From what I’ve read about his views, we are political and ideological opposites.

“At the Dialog conferences I’ve been to, there were a wide variety of people, with a wide variety of opinions, some I agreed with, some I didn’t. I can’t speak to every person named in the reporting, but my experience was not of a single ideological gathering,” he added.

Bush, who has become an advocate against deepfake technology and executive-produced the documentary Another Body on the topic, said in a statement posted to social media that she attends conferences to promote the film.

“You can imagine my surprise to learn that a conference I was invited to as a guest who could counter the ‘it’s-all-progress’ narrative of this seeming runaway AI race was founded by someone you could not pay me to be in a room with, let alone charge me money to be in a room with,” Bush wrote. “To be clear, that individual was not present, was never brought up during my experience there at all, and as I’ve since learned, he has not been involved whatsoever in approximately 15 years.”

Yet Bush still defended the controversial conference along similar lines as Gordon-Levitt, saying it is important to hear other perspectives.

“I did find the conference weekend valuable, in the same way I find it valuable to meet with and important to engage with people who see the world differently than I do in addition to the work I do alongside like-minded allies,” she wrote. At the same time, “I do wish I would have researched the event beforehand, but even if I had, I probably still would have gone because I firmly believe that having women standing up for women (and ringing alarm bells about our common and dangerous experiences with emerging technology) in rooms like these is of paramount importance.”

Brolin previously responded to an inquiry about his involvement via a rep, who told THR that the No Country for Old Men actor would “like to know what the fuck he got himself into.”

The materials leaked to THR identify the set of session topics at this year’s conference in Dublin. There is a heavy emphasis on geopolitics and technology topics. Several relate to divisive issues, like “Bring Back Nuclear,” “Disinformation & Deepfakes,” “Battlefield Technologies,” “Democracy Under Surveillance,” “Taiwan and the AI Race” and “Three Predictions in Iran.” They also reflected more individual-oriented topics, with “How’s Your Sex Life,” “It’s Fun to Be in Charge,” and “Research-Based Longevity Hacks” sitting alongside some very dark themes, with topics including “Build-a-Cult” and “Navigating WWIII.”

Dialog also features an internal dating function, used to match members with each other, and offers discussions on book recommendations, technology’s effect on humanity and the future, among other topics.