Brittney Griner's legal team has appealed against the American basketball star's guilty verdict and nine-year prison sentence on drug smuggling charges in Russia
Griner was arrested for carrying vape cartridges containing with marijuana in a Moscow airport in February amid soaring tension between Washington and Moscow
The athlete was on her way to Yekaterinburg, in western Russia, to play for a local team during the WNBA's off-season
Griner pleaded guilty to the charge but sought leniency, saying that she packed the cartridges inadvertently and marijuana was prescribed to her by a doctor in the U.S.
Secretary of State Antony Blinken said the U.S. had put forward a "substantial proposal" to Russia for a potential prisoner exchange.
The Kremlin initially gave a measured response, indicating that no swap would be considered until there was a verdict in Griner's case.
Over the weekend, however, Russian officials confirmed that negotiations were underway and acknowledged that Moscow was indeed seeking an exchange for Bout.