Moscow and Washington have been in talks about a new prisoner exchange, in a rare moment of dialogue with tensions soaring over Russia's invasion of Ukraine.
A Russian arms dealer, a former teacher and a US basketball star are among the potential candidates for the swap.
US basketball star Brittney Griner has been sentenced to nine years in prison in Russia after she was arrested at a Moscow airport in February for possessing vape cartridges with cannabis oil. The arrest came just days before Moscow launched its offensive in Ukraine on 24 February.
She said it was prescribed by a US doctor to relieve pain from her many injuries.
The 31-year-old Phoenix Mercury player came to Russia to play basketball for a club in Russia's Yekaterinburg during the off-season.
The two-time Olympic gold medalist and Women's NBA champion was convicted on drug smuggling charges.
Former US marine Paul Whelan, 52, was arrested in December 2018 and accused by Russian security services of spying.
He was detained on a visit to Moscow to attend a wedding when he took a USB drive from an acquaintance, which he said he thought contained holiday photographs.
The former security official at a vehicle parts company - who also has Irish, British and Canadian passports - was sentenced to 16 years on espionage charges in June 2020.
During his closed-door trial, Mr Whelan insisted he was innocent.
A teacher at an international school in Moscow, US citizen Marc Fogel was in June sentenced to 14 years in prison on charges of "large-scale" cannabis trafficking.
Russian customs officers said they found marijuana and hash oil in Mr Fogel's luggage when he arrived from New York at Moscow's Sheremetyevo airport.
Mr Fogel said the marijuana was prescribed in the United States for medical purposes after a spinal operation.
Russia has not made the use of cannabis legal for medicinal purposes.
Russian officials said Mr Fogel was earlier employed by the US embassy in Moscow and benefitted from diplomatic immunity until May 2021.
Russian arms trafficker Victor Bout was in 2012 sentenced to 25 years in a US jail after he was accused of arming rebels in some of the world's bloodiest conflicts.
The 55-year-old is considered the highest-profile Russian imprisoned in the United States.
The former Soviet air force officer and polyglot was arrested in Thailand in 2008 during a sting operation in which US agents posed as Colombia's FARC rebels seeking weapons.
He inspired the 2005 arms smuggling movie 'Lord of War' starring Nicholas Cage and was dubbed 'Merchant of Death' by former British minister Peter Hain for supplying weapons to war-torn Angola and Liberia.