TOKYO — Former Chicago Bulls basketball star Dennis Rodman arrived in North Korea on Tuesday and hopes to meet leader Kim Jong Un, at a time when President Trump is said to be trying to set up a secret channel to North Korea.

Rodman’s trip has sparked speculation that he may be traveling to free American citizens being held by North Korea, perhaps as a first and important step toward lessening tensions between Washington and Pyongyang.

Before Rodman arrived in Pyongyang, North Korea arranged with U.S. authorities to free one of the four Americans it was holding: Otto Warmbier, 22, a University of Virginia student who was held for 17 months for trying to steal a propaganda poster as a souvenir. He was flown out of the country Tuesday in a U.S. medical evacuation plane. The North Koreans said he contracted botulism and fell into a coma after receiving a sleeping pill following his March 2016 trial, his family said.

Trump, who had Rodman on his “Celebrity Apprentice” show for two seasons, recently called Kim a “smart cookie” and said he would be “honored” to meet him. Rodman has met Kim on previous trips to North Korea, serenading him from the basketball court and even holding his baby daughter.

That means Rodman is Trump and Kim’s only mutual acquaintance.

Multiple people involved in unofficial talks with North Korea say the Trump administration has been making overtures toward the Kim regime, including efforts to set up a secret back channel to the North Korean leader using “an associate of Trump’s” rather than the usual lineup of North Korea experts and former officials who talk to Pyongyang’s representatives.

It is not clear whether the Rodman trip is part of that effort, and the former basketball player known as “The Worm” declined to answer reporters’ questions when he arrived in Pyongyang on his fifth visit to the country.

“I will discuss my mission upon my return to the U.S.A,” he told reporters earlier at Beijing airport. He said he hoped to do something “pretty positive” in North Korea but poured cold water on the suggestion he might be able to secure the release of the American detainees.

Asked if Trump knew about his trip, Rodman said: “I’m pretty sure he’s happy at the fact I’m over here trying to accomplish something we both need.”

The NBA hall of famer, who is 56, discussed his trips to North Korea with Trump before the businessman was elected president, according to associates of Rodman.

Rodman endorsed Trump in 2015, tweeting that Trump “has been a great friend for many years. We don’t need another politician, we need a businessman like Mr. Trump! Trump 2016.” Trump responded: “Thank you DennisRodman. It’s time to MakeAmericaGreatAgain! I hope you are doing well!”

Rodman has called Kim a “friend for life.”

In a surreal scene, the basketball player and his agent, Chris Volo, were photographed in Beijing wearing T-shirts bearing the logo for “PotCoin,” which markets itself as “banking for the marijuana industry.” PotCoin tweeted a photo of the pair, with the words “stay tuned.”

Rodman was traveling with Volo and Columbia University geneticist Joe Terwilliger, who has accompanied Rodman on previous trips.

The State Department declined to comment on Rodman’s trip, but administration officials have told other media outlets that the athlete was traveling in a private capacity.

Still, the trip fueled speculation that something more was underway.

“One thing we know is that Trump is transactional,” said one person who works on North Korea issues, speaking on condition of anonymity due to the sensitivity of the discussions. “He’s not a member of the Foreign Service – his focus is on getting things done.”

Daniel Pinkston, a North Korea analyst who advised Rodman after an earlier trip, said the former basketball star had a “long-standing invitation” to return to North Korea.

“I heard that the North Korean Foreign Ministry had a desire for a visit by him to reduce tensions with the United States. They’ve been looking at ways to do that,” Pinkston said.

Rodman has now been to North Korea five times, but he has come under heavy criticism for appearing to appease a man who leads a regime that is vowing a nuclear strike on the United States.