A senior Russian diplomat has confirmed publicly that Moscow is seeking the return of convicted arms dealer Viktor Bout in negotiations with U.S. officials for the return of detained Americans.

According to an interview in the Russian official news organ Tass, Aleksandr Darchiev confirmed over the weekend that Bout was part of the ongoing negotiations. Darchiev is director of the North American department at the Russian Foreign Ministry.

Asked about the prospect of a prisoner exchange in which Bout might be offered for detained WNBA basketball star Brittney Griner and businessman Paul Whelan, Darchiev confirmed that “we are taking into account all these people you are naming.”

Darchiev then said explicitly: “Russia has been pursuing Viktor Bout’s release for a long time, but we should leave the details to the professionals, who act on the principle of ‘do no harm.’”

On Monday, the defense team for Griner, who was recently sentenced to more than 9 years by a Moscow court for drug smuggling charges, said they are appealing the verdict.

Maria Blagovolina, a partner at the law firm that has represented Griner, did not detail the grounds for Griner’s appeal. Griner’s legal team has said that her appeal would most likely take up to three months to be adjudicated.