“Currently, talks are underway on exchanging Bout for Griner,” TASS reported, referencing information provided by “a source in the Public Monitoring Commission.”

The Biden administration offered to swap Bout for Griner but negotiations are still premature, based on an account from a nongovernment inside source, Forbes reports.

Since February, Griner, 31, has been detained in Russia after Russian customs officials allegedly found a vape cartridge containing hash oil in her luggage at a Moscow-area airport. If convicted, she faces a maximum sentence of 10 years in prison, according to the Insider.

Bout, who was given the moniker of “Merchant of Death,” was issued a 25-year sentence in federal prison by a New York federal court in 2011 for plotting to sell millions of dollars worth of weapons to the Revolutionary Armed Forces of Colombia, or FARC, a Marxist-Leninist guerrilla group.

Bout worked as a translator in the Soviet army before starting an air-freight company that transported weapons he supplied during the 1990s and early 2000s to African and Asian militias and rebels. He was arrested in 2008 during a sting operation orchestrated by the U.S. Drug Enforcement Agency, Forbes reports.

However, officials expressed concern about whether Biden will approve the exchange of Griner for an infamous Russian arms trafficker, as he would be returning to a country led by Putin, who Biden considers a “war criminal.” 

“There’s a problem with releasing a convicted arms trafficker for Griner, whose drug possession would probably only be a fine in the U.S.,” Shira Scheindlin, a retired federal judge who conducted the Bout trial, told Forbes. “It would be better if Bout — who has already served too much time in my opinion — was exchanged for both Brittney Griner and Paul Whelan. Then there would be some moral equivalency about which few could complain.”

In April, the Biden administration negotiated the release of Trevor Reed, a former Marine detained in Russia for allegedly assaulting a Moscow police officer. In exchange, Biden commuted the sentence of Konstantin Yaroshenko, who was convicted for scheming to import $100 million worth of cocaine into the United States.