LONDON (Reuters) - Russia is holding at least a dozen American citizens in jail, including journalists and active duty soldiers. 

Below are details about the best known Americans currently in detention, why Russia is holding them and what the United States is doing to get them back.

The United States warns its citizens against all travel to Russia. 

EVAN GERSHKOVICH

A Wall Street Journal reporter accredited by Russia to work there, Gershkovich was arrested in March 2023 in the Urals city of Yekaterinburg and accused of trying to obtain defence secrets and espionage.

He and his newspaper strongly reject the charges and the U.S. government has designated him as wrongfully detained, meaning it must seek ways to get Gershkovich released.

Russian President Vladimir Putin said this month Washington was taking "vigorous steps" to secure Gershkovich's release, but that ongoing talks needed to be conducted away from the media.

Gershkovich, 32, has been held in Moscow's Lefortovo prison since his arrest, which has been extended multiple times. No date has been set for his espionage trial.

PAUL WHELAN

A former U.S. marine holding U.S., British, Irish and Canadian citizenship, Whelan was arrested in 2018 and subsequently handed a 16-year sentence for espionage. He denied the charges.

At the time of his arrest, Whelan was head of global security for a Michigan-based car parts supplier. Russian investigators said he was a spy for military intelligence and had been caught red-handed with a computer flash drive containing classified information.

Whelan, 54, did not figure in a U.S.-Russia prisoner exchange in December 2022 involving U.S. basketball star Brittney Griner, despite speculation that he would be swapped. Griner was traded for Russian arms trafficker Viktor Bout.

The U.S. has designated Whelan as wrongfully detained.

ALSU KURMASHEVA

A dual citizen of the U.S. and Russia, Kurmasheva is a 47-year-old Prague-based reporter for Radio Free Europe/Radio Liberty (RFE/RL), a U.S. government-funded media outlet designated by Russia as a foreign agent.

She was arrested in the Russian city of Kazan in October while visiting her elderly mother. Authorities initially charged her with failing to register as a foreign agent, but later also charged her with spreading "fakes" about the Russian army, which risks up to 15 years in jail.

Kurmasheva's husband has petitioned the U.S. to designate her as wrongfully detained.

GORDON BLACK

An active duty U.S. staff sergeant based in South Korea, Black was detained on May 2 in Vladivostok in the Russia's Far East on suspicion of stealing 10,000 roubles ($110) from his Russian girlfriend. Citing local prosecutors, Russian independent media reported he had also subsequently been charged with threatening to kill her.

The Pentagon said Black had broken army rules by travelling to Russia without authorisation, having passed through China.

His trial began on June 6 in Vladivostok. Black has agreed to testify but has not yet entered a plea.

ROBERT GILMAN

A former U.S. marine, Gilman was sentenced to 4-1/2 years in prison in October 2022 for attacking a police officer on a train while he was drunk.

Gilman, who his lawyers said had come to Russia to study, told the court he did not remember the incident but had "apologised to Russia" and to the officer.

KSENIA KARELINA

A dual U.S.-Russian national, Karelina was detained on treason charges in February while visiting family in Yekaterinburg and faces up to 20 years in prison if convicted.

Russia's Federal Security Service (FSB) has accused the Los Angeles resident of collecting funds for a Ukrainian organisation whose ultimate beneficiary was Ukraine's army. Her family said she donated about $50 to a New York-based nonprofit that donates non-military aid to Ukraine.

MARC FOGEL

A former schoolteacher who was previously employed at the U.S. Embassy in Moscow, Fogel is serving a 14-year sentence for drug smuggling after he was detained in Moscow's Sheremetyevo airport in August 2021 with 17 grams of marijuana - which he said he uses for medical reasons - in his luggage.

At the time of his arrest, Fogel, who is in his early 60s, worked at the now-shuttered Anglo-American School in Moscow.

ROBERT ROMANOV WOODLAND

A U.S. citizen adopted from Russia as a child, Woodland was detained in January on drug possession charges which can carry up to 20 years in prison.

A Facebook account in his name indicated he had been working as an English teacher and lived outside Moscow. A date has not yet been set for his trial.

EUGENE SPECTOR

Currently serving a 3-1/2-year sentence for bribery, Spector, who was born in Russia and then moved to the United States, was charged last August with espionage.

Before his 2021 arrest, he served as chairman of the board of Medpolymerprom Group, a company specialising in cancer-curing drugs, state media said. Spector had pleaded guilty to helping bribe an assistant to an ex-Russian deputy prime minister.

(Reporting and writing by Lucy Papachristou; editing by Guy Faulconbridge and Gareth Jones)