Rodman's trip has sparked speculation that he may be traveling to free some or all of the four American citizens currently being held by North Korea, perhaps as a first and important step toward lessening tensions between Washington and Pyongyang.
Trump, who had the basketballer on his "Celebrity Apprentice" show twice, has recently called Kim a "smart cookie" and has said he would be "honored" to meet him.
Multiple people involved in unofficial talks with North Korea say that the Trump administration has been making overtures toward the Kim regime, including trying to set up a secret back channel to the North Korean leader using "an associate of Trump's" rather than the usual line-up of North Korea experts and former officials who talk to Pyongyang's representatives.
It is not clear if the Rodman trip is part of that effort or not.
"But one thing we know is that Trump is transactional," said one person who works on North Korea, speaking on the 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."
The former Chicago Bull had discussed his trips to North Korea with Trump before the businessman was elected president, according to associates of Rodman.
The State Department did not respond to a request for comment on Rodman's trip, but administration officials had told other media that the basketballer was traveling in a private capacity.
Daniel Pinkston, a North Korea analyst who advised Rodman after an earlier trip, said that the basketballer 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 at least four times, including one trip during which he sang happy birthday to Kim from the basketball court, but has come in for heavy criticism for appearing to appease a man who leads a regime that is vowing a nuclear strike on the United States.
Rodman's latest visit coincides with a rapid succession of missile tests from North Korea and warnings that the state has the technology to strike the mainland United States. It also comes as four Americans are being held in North Korea.
The North Korean mission at the United Nations confirmed that Rodman had flown from Beijing to Pyongyang Tuesday morning, and television crews at the airport showed Rodman and his agent, Chris Volo, at the airport. Another regular member of Rodman's entourage, Columbia University geneticist Joe Terwilliger, was also on the trip.
When approached by CNN, Rodman declined to comment on his trip but said "see you Thursday."
The fact that Rodman was going for such a short period of time raised expectations that he might be going to free the four Americans being held by North Korea.
"This visit will be judged not by who he takes with him but by who, if anyone, he brings back," said Scott Snyder, a Korea expert at the Council on Foreign Relations.
A former Virginia man, Kim Dong-chul, was arrested shortly after Warmbier, this time on accusations of espionage, and has been held ever since.
In April and May, North Korea detained two other Korean Americans, both of them affiliated with the Pyongyang University of Science and Technology, a private institution run by Korean American Christians.
Previous detainees have been released after visits from high-profile Americans, including former presidents Jimmy Carter and Bill Clinton. But efforts to convince North Korea to release the men currently held have not been successful so far.
Rodman was lambasted on previous trips for refusing to pursue the case of an American, Kenneth Bae, who was being held in North Korea at the time.
On one of his trips to North Korea, in January 2014, Rodman took a group of retired NBA stars to Pyongyang for what one of them called "basketball diplomacy" with North Korean players. The trip quickly turned into a debacle, with sponsors dropping some of the players, who went on CNN to try to explain why they were there.
But it went from bad to worse when Rodman went on a tirade in another interview, and then sang happy birthday to leader Kim Jong Un, singing "happy birthday dear Marshal" to him from the court. The trip was captured in the documentary "Big Bang in Pyongyang."
In a previous trip, Rodman spent a significant amount of time with Kim and his wife, even holding their baby daughter. He and his friends, Terwilliger and Volo, are the only Americans known to have met Kim.
People familiar with the basketballer's trip preparations said that Rodman was due to travel to Pyongyang last month but the trip was delayed. A North Korean diplomat at the United Nations disputed this, saying that Rodman had not been invited by the foreign ministry but by a sports-related agency.
Some of Rodman's previous interactions with Trump had been captured on television.
Rodman appeared on "Celebrity Apprentice" in 2013, when Trump's children Eric and Ivanka were also judges on the show. But Trump fired Rodman for spelling his wife Melania's name wrong. "Simply. . . Milania" the words above a photo of the now-first lady read.
"The fact is, you spelled her name wrong, so Dennis, you lost," Trump said. "Dennis, you're fired" Trump told the basketballer, who was wearing his trademark sunglasses and adorned with piercings.
Rodman had earlier appeared on Celebrity Apprentice in 2009, with Trump calling the basketballer "a piece of work."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)