Romanian border police confirmed to ABC News that Kanter's travel documents had been canceled by his home country and he was not allowed to enter the country.
Kanter, 25, a popular player with the Oklahoma City Thunder, is a supporter of Pennsylvania-based preacher Fethullah Gülen, a staunch critic of Erdogan who the Turkish president has blamed for failed July 2016 coup that took place in the country. Erdogan has called for the extradition of Gülen, who has denied involvement in the attempted coup.
"You know he attacked the people in Washington," Kanter says in the video. "He's a bad, bad man. He's a dictator."
Kanter is now headed back to the U.S. via London, according to a Romanian Border Police spokesperson that spoke to The Associated Press about the matter. It is unclear how he is able to travel with an invalid passport.
The AP reports that Kanter was traveling in Europe and Indonesia with the Enes Kanter Light Foundation, his newly-created charity that focuses on children living in poverty. When he arrived in Bucharest he was reportedly detained.
In addition to the video, Kanter also posted a photo of himself giving the thumb's up on Twitter, acknowledging that his travel restrictions had been lifted.
He promised to elaborate on the situation at a press conference in New York, which is expected later today.
"Gonna give press conference tomorrow in NY," he wrote. "Got lots of things to say with lots of crazy stories."
Kanter's Twitter account was banned in Turkey following the attempted coup, Hurriet Daily News reported.
During the doomed July affair, in which over 300 people were killed and tens of thousands more were detained, Kanter posted an article on social media that was critical of Erdogan, and a news clip that contained Gülen's denial of involvement in the affair.
Kanter wrote about Gülen in 2016, according to Hurriet Daily News, a Turkish newspaper. "My mother, father, siblings and all of my relatives can be sacrificed on Gülen’s way. I can give my head on his way. May God take from my life and give every second of it to my brave preacher,” he wrote.
Kanter's support for Gülen has caused a rift within his own family, according to the BBC, which reported that Kanter's father published a letter disowning his son in the weeks following the failed coup attempt.