The US has offered Russia a prisoner swap deal, in an effort to bring home two jailed Americans, including basketball star Brittney Griner.
The Women's NBA player was arrested at Sheremetyevo Airport in Moscow on 17 February as she made her way back to Russia to play for UMMC Yekaterinburg, during the US Women's National Basketball Association off-season.
Police said they found vape canisters containing cannabis oil in her luggage.
Ms Griner, 31, who has been in custody since then, pleaded guilty to charges that could land her a prison sentence of up to a decade.
But she testified at her drug possession trial that an interpreter translated only a fraction of what was being said while she was detained and that officials told her to sign documents, but "no-one explained any of it to me".
US Secretary of State Antony Blinken said he would raise the matter of both her detention and that of Paul Whelan -arrested in Russia in 2018, and accused of spying – in a call next week with Russia's foreign minister.
Mr Blinken and Sergei Lavrov have not spoken since the war in Ukraine began.
The Secretary of State's comments marked the first time the US government has publicly revealed any concrete action it has taken to secure the release of Ms Griner.
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He described the prisoner swap suggestion as a "substantial proposal" adding: "Our governments have communicated repeatedly and directly on that proposal, and I'll use the conversation to follow up personally and, I hope, to move us toward a resolution."
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Mr Blinken did not offer details on the proposed deal outlined to the Russians, but US officials suggested it is similar to the prisoner swap that secured the release of marine veteran Trevor Reed in April.
Russia has made no secret of its desire for convicted Russian arms dealer Viktor Bout to be freed from American prison and the officials would not rule out that Bout's release is on the table.
Once labelled the "Merchant of Death," he was sentenced to 25 years in prison in 2012 on charges that he conspired to illegally sell millions of dollars of weapons.
President Joe Biden, who authorised the Reed prisoner swap after meeting with his parents, signed off on the deal being offered in this Griner/Whelan case, officials said.
John Kirby, a White House national security spokesman, said: "The president and his team are willing to take extraordinary steps to bring them home."
Mr Whelan, a former US marine and corporate security executive from Michigan, was sentenced in 2020 to 16 years in prison on espionage charges.
He and his family have vigorously asserted his innocence. The US government has denounced the charges as false.
Ms Griner acknowledged in court she had vape cartridges containing cannabis oil in her luggage when she arrived in Moscow in February but contends she had no criminal intent and packed the cartridges by mistake as she had been in a hurry.