The White House on Tuesday said it was reassuring to see video footage of Paul Whelan, a US citizen jailed in Russia over what Washington calls bogus espionage charges, and called on Moscow to release him immediately.
The former marine was featured in a video segment released by state-controlled news network Russia Today on Monday night.
Dressed in a black prison uniform and matching hat, Mr Whelan appears alongside other inmates in footage showing different parts of the prison. He can be seen using a sewing machine and visiting the cafeteria.
Arrested in 2018, Mr Whelan was convicted of spying charges in 2020 and sentenced to 16 years in a penal colony in the Mordovia region.
He strongly denies the charges against him.
“It was reassuring to see that he remains, and this is to use his brother's words, 'unbowed',” White House spokeswoman Karine Jean-Pierre told reporters.
“Paul continues to show tremendous courage.
“Russia should release him immediately.”
In December, US basketball star Brittney Griner was freed in a prisoner exchange with Russia. She had been traded for Russian citizen Viktor Bout, a convicted arms dealer who had been jailed in the US.