Russian prosecutors asked a judge to jail WNBA player Brittney Griner for nine and 1/2 years on drug charges Thursday, close to the maximum, as talks between Russia and the U.S. on a possible prisoner exchange involving the basketball star remain deadlocked.

Griner, 31, a two-time Olympic Gold medalist, pleaded guilty to smuggling last month on charges that carry a possible prison sentence of up to 10 years in Russia, saying her action was unintentional. She was arrested in February at a Moscow airport after customs officials said they found vape canisters containing cannabis oil in her luggage.

Her plight has generated widespread public support in the U.S., where President Joe Biden’s administration has pledged to pursue “every avenue to bring Brittney home.” Secretary of State Antony Blinken said last week that the U.S. had made a “substantial” offer to Russia for an exchange involving Griner and former U.S. Marine Paul Whelan, who was jailed in 2020 on espionage charges that he denies.

The U.S. is ready to swap them for Viktor Bout, an arms dealer known as the “merchant of death,” according to people with knowledge of the matter.

Bout, who was sentenced to 25 years in the U.S. in 2012, has long been the subject of Kremlin efforts to return him to Russia. Even so, officials in Moscow have been leaning toward rejecting the prisoner swap because they regard its terms as unequal, people familiar with the Kremlin’s thinking say.

Russia would agree to swap Griner for Bout or a two-for-two exchange, a Russian official and a person close to the Kremlin said.

A Russian official asked via a backchannel to include in any deal Vadim Krasikov, a former official with links to the domestic spy agency who was convicted of murder in 2021 in Germany, people familiar with the conversations said. Another potential target for Russia could be Vladislav Klyushin, a Kremlin insider extradited from Switzerland to the U.S. in December on insider-trading charges, several people in Moscow with knowledge of the matter said.

The negotiations are complicated by the virtual collapse in relations between Russia and the U.S. since President Vladimir Putin’s invasion of Ukraine in February. The U.S. is backing Ukraine’s defense with supplies of billions of dollars in weapons and financial aid.

Despite the tensions, Biden sanctioned a surprise deal in April to exchange Konstantin Yaroshenko, a Russian pilot sentenced in 2011 to 20 years for conspiracy to smuggle cocaine, for Trevor Reed, a former U.S. Marine who was serving nine years in Russia after being convicted in 2020.