President Donald Trump hosted a previously undisclosed dinner with Facebook CEO Mark Zuckerberg and Facebook board member Peter Thiel at the White House in October, the company told NBC News on Wednesday.

The meeting took place during Zuckerberg’s most recent visit to Washington, where he testified before Congress about Facebook’s new cryptocurrency Libra. Zuckerberg also gave a speech at Georgetown University the week before, detailing his company’s commitment to free speech, and its resistance to calls for the company to crack down on misinformation in political advertisements.

“As is normal for a CEO of a major U.S. company, Mark accepted an invitation to have dinner with the President and First Lady at the White House,” a Facebook spokesperson said in an emailed statement.

A source familiar with the dinner told NBC News that Thiel was also present. It is unclear why the meeting was not made public or what Trump, Zuckerberg and Thiel discussed.

The White House declined to comment.

The dinner was the second meeting between Zuckerberg and Trump in a month. Zuckerberg also met with the president in the Oval Office during a September visit to the capital.

Thiel, one of seven Facebook board members, is one of the few outspoken conservative figures in Silicon Valley. A major donor to Trump’s campaign, Thiel is also the chairman of Palantir, a private data technology company that has become one of the largest recipients of government defense contracts with the United States government since Trump took office.

Thiel famously bankrolled an invasion of privacy lawsuit that effectively bankrupted the gossip website Gawker. Zuckerberg’s speech at Georgetown, which he delivered on the same trip in which he met with Trump, was titled “Standing for Voice and Free Expression.”

The Facebook chief is not the only high-profile tech executive to have met with the president recently. On Wednesday, Trump and Apple CEO Tim Cook toured an Apple manufacturing plant in Austin, Texas.

Trump and Cook have maintained a very public working relationship as the Apple CEO seeks to keep Apple products exempt from the president’s tariffs on China.