"I was told I was not under arrest, but all they wanted me to do was answer some questions," Miller explained.

Miller told Fox News that he was being questioned as part of "two secret investigations" led by Brazilian Supreme Court Justice Alexandre De Moraes.

"In Brazil, a Supreme Court justice is also given the ability to issue subpoenas, have people arrested, and more," Miller said. "They are untenable."

Miller explained that there has been tension between Brazilian President Bolsonaro and the Supreme Court.

The Washington Post reported that in recent weeks de Moraes signed off on the arrest of multiple supporters of Bolsonaro as his office oversees a national investigation into misinformation.

The Post reported that Bolsonaro has described the investigations — some of which are targeting his family members — as an unfair infringement of his authority as president and has accused the Supreme Court of abusing its constitutional power. The Post reported that last month Bolsonaro submitted a request to impeach de Moraes. The senate quickly tossed it out as baseless.

Miller said that during Tuesday's questioning he requested a lawyer and contacted the U.S. Embassy, which ultimately came to assist.

"I don’t speak Portuguese and none of them spoke English," he said.

Miller, the CEO of GETTR, which launched on July 4, was asked to provide the names of everyone who was helping with the platform in Brazil. The platform has attracted nearly a quarter-million Brazilians — including two sons of the president, Eduardo and Flavio Bolsonaro, as well as the president himself.

Miller told Fox News he did not share the identities of the individuals working on GETTR in Brazil.

Miller said he was also asked whether he felt a platform with software like GETTR could be used to organize an event in Brazil like the one at the U.S. Capitol on Jan. 6.

"We didn’t even kick off until July 4, so why are you asking me about Jan. 6?" Miller recalled.

"This was a political brushback pitch because we support free speech," Miller said, adding that he assumes it has to do with the "feuding between the supreme court and the president," and an effort to get him to "never come back to Brazil and write off proud patriots."

"If anything, I’m more motivated now than ever," Miller said.

Miller, though, said that Americans "take for granted" the legal system in the United States, even though many have "frustrations and trouble with it."

"It is scary stuff when you see a leader like Bolsonaro who bucks the system and challenges the system, who represents a change to the status quo, where free speech comes under attack," Miller said, adding that the "deep state and witch hunts in other countries are more serious" than in the U.S.

Miller told Fox News he feels that his detainment would have "a chilling effect."

"They are trying to scare off anyone who might talk about things like free speech," Miller said. "They want to use the rule of law, as they would define it, for anything they don’t like."

Meanwhile, Bolsonaro, during a speech on Tuesday, didn’t address Miller by name, but slammed de Moraes, essentially blaming the Supreme Court justice for Miller’s brief detainment.

"We are increasingly conservative. We are increasingly respectful of our law and Constitution. And we will no longer allow people like Alexandre de Moraes to continue to whip our democracy and disrespect our Constitution," Bolsonaro said. "He had every opportunity to act with respect for all of us. But he didn't act in that way, as he still doesn't. As he just intercepted an American citizen to be questioned about anti-democratic acts."

Bolsonaro called the move "a shame to our country, sponsored by Alexandre de Moraes."

Miller told Fox News that he is "honored and grateful" Bolsonaro mentioned the incident.

"I can't say enough positive things about Brazil and the people of Brazil, and the people who make up our user base," Miller said. "Free speech is a real issue, not just in the U.S., but around the world."