American basketball star Brittney Griner returned to a Russian courtroom on Tuesday for her drawn-out trial on drug charges that could bring her 10 years in prison if convicted.

The trial of the two-time Olympic gold medalist and Phoenix Mercury standout began July 1 but only four sessions have been held, some them lasting only a few hours. In one of them she acknowledged that she was carrying vape canisters containing cannabis oil when she was arrested at a Moscow airport in mid-February, but said she had no criminal intent.

The slow-moving trial and her five months of detention have raised strong criticism among teammates and supporters in the United States, which has formally declared her to be “wrongfully detained,” a designation sharply rejected by Russian officials.

Griner was arrested amid high U.S.-Moscow tensions ahead of Russia sending troops into Ukraine later that month. Some supporters contend she is being held in Russia as a pawn, possibly for a prisoner swap. American soccer notable Megan Rapinoe last week said “she’s being held as a political prisoner, obviously.”

However, even after the conflict broke out, Washington and Moscow brokered a prisoner trade in April when American Trevor Reed, imprisoned on a conviction of assaulting a police officer, was released in exchange for Konstantin Yaroshenko, a Russian convicted in the U.S. of drug smuggling.

The Russian Foreign Ministry last week lashed out at the U.S. contention that Griner is being wrongfully detained and said Russian laws should be respected.

“If a U.S. citizen was taken in connection with the fact that she was smuggling drugs, and she does not deny this, then this should be commensurate with our Russian local laws, and not with those adopted in San Francisco, New York and Washington,” spokeswoman Maria Zakharova said.

“If drugs are legalized in the United States, in a number of states, and this is done for a long time and now the whole country will become drug-addicted, this does not mean that all other countries are following the same path,” she added.

Russian media have speculated that Griner could be exchanged for prominent Russian arms trader Viktor Bout, who is imprisoned in the United States, and that Paul Whelan, an American imprisoned in Russia for espionage, may also figure in an exchange.

U.S. officials have not commented on the prospects for such a trade. Russian officials have said no exchange could be discussed until the conclusion of the legal proceedings against Griner. It is unclear how long the trial will last, but a court has authorized Griner’s detention until Dec. 20.

Previous trial sessions have included character-witness testimony from the director and captain of the Russian team that Griner played for in the off-season, along with written testimony including a doctor's letter saying he had authorized her to use cannabis for pain treatment.