While Ms Griner was arrested a week before Russia invaded Ukraine, Russian authorities did not reveal her detention until days after the war began, raising fears she was being used as currency of exchange in the global crisis.

The US State Department said it had determined Ms Griner had been “wrongfully detained”, signaling its intention to become more actively involved in the situation.

Russia’s release of Trevor R. Reed, an ill former US sailor who was sentenced to nine years in prison for assault, in late April during a prisoner swap with the US has raised hope that Ms. Griner might follow suit.

It is typical for Russian courts to prolong detention until trial, which can then take weeks. Mr. Reed’s release, for example, came after he was found guilty and spent years in a Russian prison.

Ms. Griner’s team and family have been relatively quiet about her situation.

A two-time Olympic gold medalist, Ms. Griner was one of many American players to compete for off-season international teams to supplement their WNBA salaries. She has been playing for the UMMC team in Yekaterinburg, Russia since 2014.