WASHINGTON (NewsNation) — Russia and the United States said on Friday they were ready to discuss a prisoner swap, a day after a Russian court sentenced basketball star Brittney Griner to nine years in prison for a drug offense.

The case against Griner, a two-time Olympic gold medallist and Women’s National Basketball Association (WNBA) star, plunged her into a geopolitical maelstrom after Russia sent troops into Ukraine on Feb. 24.

Russian Foreign Minister Sergei Lavrov said President Vladimir Putin and U.S. President Joe Biden had previously agreed on a diplomatic channel that should be used to discuss potential prisoner exchanges.

“We are ready to discuss this topic, but within the framework of the channel that was agreed upon by presidents Putin and Biden,” Lavrov said during a visit to Cambodia.

“If the Americans decide to once again resort to public diplomacy …, that is their business and I would even say that it is their problem.”

U.S. Secretary of State Antony Blinken said Washington was prepared to engage with Moscow through diplomatic channels established to handle the issue, and Griner’s conviction had further compounded the injustice that had been done to her.

Speaking also in Cambodia, Blinken said the sentence, “puts a spotlight on our very significant concerns about Russia’s legal system and the Russian government’s use of wrongful detentions to advance its own agenda, using individuals as political pawns.”

The Kremlin had previously warned the United States against turning to “megaphone diplomacy” in the case of Griner, saying it could only derail efforts to secure a potential swap.

Biden called Griner’s sentence “unacceptable,” and demanded her immediate release so she can be with loved ones.

Griner’s sentence could pave the way for a prisoner swap that would include the 31-year-old athlete and a prolific Russian arms dealer serving a 25-year prison term in the United States.

The United States has already made what Blinken called a “substantial offer” to secure the release of Americans detained in Russia, including Griner and former Marine Paul Whelan.

White House national security spokesperson John Kirby said after Griner’s sentencing that the United States had made Russia a serious proposal.

“We urge them to accept it,” he said. “They should have accepted it weeks ago when we first made it.”

Kirby did not provide further detail on the U.S. proposal.

Washington has offered to exchange Russian arms trafficker Viktor Bout for Griner and Whelan, sources familiar with the situation have told Reuters.

Russia had tried to add convicted murderer Vadim Krasikov, imprisoned in Germany, to the proposed swap, a source familiar with the proceedings also told Reuters.

Russia and the United States staged a prisoner swap in April, trading former Marine Trevor Reed for Russian pilot Konstantin Yaroshenko, who was serving a 20-year sentence in the United States. 

Meanwhile, a moment of silence was held for Griner at Wednesday night’s Phoenix Mercury game. Fans broke the silence with chants of “bring her home.”

Griner was arrested on Feb. 17 at Moscow’s Sheremetyevo airport with vape cartridges containing hashish oil in her luggage.

The United States argued she was wrongly detained and being used as a political bargaining chip by Moscow. Russian officials dismissed the U.S. claims, saying Griner had broken Russian law and should be judged accordingly.

Griner, who had been prescribed medical cannabis in the United States to relieve pain from chronic injuries, said she had made an honest mistake by inadvertently packing her vape cartridges as she rushed to make her flight.

She pleaded guilty to the charges against her but insisted that she did not intend to break Russian law.

Cannabis is illegal in Russia for both medicinal and recreational purposes.

Reuters contributed to this report.