...CNN spotted Rodman at Beijing International Airport, where he declined to answer questions. Rodman would be arriving in Pyongyang at a time of heightened tension between Washington and Pyongyang, which is currently detaining four Americans.

It's unclear what the purpose of Rodman's visit to the secretive country could be, but the eccentric former basketball player -- and a former contestant on Donald Trump's pre-presidency reality TV show "Celebrity Apprentice" -- is one of the only Americans to have met current North Korean Supreme Leader Kim Jong Un.

When asked by CNN journalists in Pyongyang, unnamed North Korean officials confirmed that Rodman is expected to arrive in Pyongyang Tuesday. They gave no further details.

Rodman has visited the country at least four times, with three of the visits taking place between 2013 and 2014. A senior US official said the State Department was aware Rodman was planning to travel to North Korea, but stressed he is not there in any official capacity.

His last visit came in January 2014, when Rodman and a group of other former NBA players took part in an exhibition basketball game. It was supposedly a birthday gift for Kim who's said to be a big basketball fan.

Rodman was filmed leading a sing-along of "Happy Birthday" to the North Korean leader, a man he calls a friend and a "very good guy," but is widely seen as a brutal dictator who once lauded the execution of his own uncle.

Rodman has described his series of trips to North Korea as a "basketball diplomacy" project and defended the trip for Kim's birthday in a CNN interview saying it was a "great idea for the world." (...)