Former NBA player Dennis Rodman plans to travel to Russia to advocate for the release of WNBA player Brittney Griner, who was sentenced to nine years in jail on drug charges.

In late July, the State Department reached out to Russia to accept a deal for the release of Griner and another detainee, amid tense relations between the two sides over the war in Ukraine.

While attending a sneaker convention in Washington, D.C., Rodman revealed he was approved to travel to Russia amid the country's strained relationship with the U.S.

"I got permission to go to Russia to help that girl," Rodman told NBC News on Saturday while visiting a restaurant. "I'm trying to go this week."

Rodman, 61, retired from the NBA in 2000. He frequently drew attention for his eccentric personality and flamboyant lifestyle.

The NBA Hall of Famer has a history of informal diplomacy with international leaders who have tense relationships with the U.S. Over the last decade, Rodman developed a relationship with North Korean leader Kim Jong Un.

The five-time NBA champion has made several visits to the country. In June 2017, Rodman presented Kim with a copy of Donald Trump's book, "The Art of the Deal."

Prior to that, Rodman made a trip to North Korea in January 2014, where he sang "Happy Birthday" to Kim, a Chicago Bulls fan.

Rodman later wrote a letter to Kim, pleading for the release of imprisoned American Kenneth Bae. Rodman credits himself with helping secure Bae's freedom.

During an interview with CNN in May 2016, Bae acknowledged Rodman's role in his release from North Korea.

"I thank Dennis Rodman for being a catalyst for my release," Bae said at the time. "He brought attention to my plight."

Rodman also made a trip to Russia in 2014 after a request from Russian President Vladimir Putin. Rodman called Putin "cool," following his trip to Moscow.

Although Rodman plans to make a trip to Russia for Griner, the State Department has issued a travel advisory, discouraging Americans from visiting the country.

Rodman doesn't need permission from the U.S. government to travel to Russia but is required to obtain a visa to enter Russia.

"Do not travel to Russia," the State Department stated in its Level 4 advisory. The State Department warned U.S. citizens to avoid traveling to Russia due to the "unprovoked and unjustified invasion of Ukraine, the potential for harassment against U.S. citizens by Russian government security officials," and possible "wrongful detention."

Nonetheless, Rodman appeared confident that his informal diplomacy methods and history with Putin will help Griner.

"I know Putin too well," he said.

Since Griner's imprisonment in Russia, U.S. officials have maintained she was wrongfully detained.

Dennis Rodman
Dennis Rodman attends the Comedy Central Roast of Bruce Willis at Hollywood Palladium in Los Angeles, July 14, 2018. Rich Fury/Getty Images
Read more