Dennis Rodman is back in North Korea, the former NBA star announced this week, with help from a marijuana cryptocurrency startup. Rodman, who has made several controversial visits to North Korea, tweeted a photo of himself holding an airline ticket for the state-owned Air Koryo on Tuesday. In a subsequent tweet, he thanked PotCoin, a digital currency for buying and selling weed, “for sponsoring my mission.”

The purpose of Rodman’s visit remains unclear, though it comes amid heightened tensions between the US and North Korea over Pyongyang’s nuclear program. Four Americans are also currently detained in North Korea.

In a press release announcing the visit, PotCoin said Rodman will provide more details about his “historic” trip upon returning to the US. The weed startup also described him as having “long-time friendships” with both President Donald Trump and Kim Jong Un, the autocratic leader of North Korea. Rodman has previously appeared on the Trump-hosted reality show The Apprentice, and endorsed Trump during the 2016 presidential campaign. He also described Kim as “a friend for life” after visiting North Korea in 2013, and has drawn criticism for his public appearances alongside the dictator.

Speaking to CNN before boarding his flight, Rodman said hopes to do “something that's pretty positive” during his trip, though he said he did not intend to bring up the detained Americans during any discussions with North Korean leaders. “Well that's not my purpose right now... My purpose is to go over there and try to see if I can keep bringing sports to North Korea," the former Chicago Bulls forward told CNN.

Rodman, wearing a PotCoin-branded t-shirt and baseball cap, said in a short video released Tuesday that the trip is “all about peace.” One of Rodman’s previous trips to North Korea was sponsored by an Irish betting company. The value of PotCoin surged following Rodman’s announcement early Tuesday.

Speaking to reporters in Tokyo, Under Secretary of State Thomas Shannon said that the US was aware of Rodman’s visit, and that he is traveling as a private citizen. “We are aware of his visit. We wish him well,” Shannon said, as reported by Reuters. “But we have issued travel warnings to Americans and suggested they not travel to North Korea for their own safety.”