The brother of an American detained in Russia since 2018 said Thursday that his family fears he will not be released for years, even as they supported the U.S. government’s agreement to a prisoner exchange that freed WNBA star Brittney Griner but left Paul Whelan behind.

Paul Whelan, a former U.S. marine who was arrested for alleged spying, listens to the verdict in a courtroom at the Moscow City Court in Moscow, Russia in June 2020. Sofia Sandurskaya, Moscow News Agency photo via AP, file

Whelan, a Michigan corporate security executive, has been jailed on espionage charges that his family and the U.S. government have said are baseless. U.S. officials said Russia refused to consider including Whelan in the Griner deal, calling it a “one or none” decision.

His brother, David Whelan, told the Associated Press that their parents spoke with Paul Whelan on Thursday – a much different conversation than their routine calls focused on Whelan’s day-to-day life and updates from the family’s home in Michigan.

“I think we all realize that the math is not going to work out for Paul to come home anytime soon, unless the U.S. government is able to find concessions,” David Whelan said. “And so I think we aren’t really sure what the way forward is.”

The family does not have any way to judge the likelihood “that he will ever be free other than by serving his entire term,” he added.

Paul Whelan, 52, was sentenced in 2020 to 16 years in prison. The situation “makes hope a little bit more difficult,” David Whelan said.

The family’s pain doesn’t change their belief that the Biden administration “made the right choice” to exchange notorious Russian arms dealer Viktor Bout for Griner, David Whelan said.

Whelan said a U.S. official visited his sister Wednesday at her home in Massachusetts to tell the family about Griner’s release, a decision that he said softened the blow of knowing his brother would stay jailed.

Pressure to include Paul Whelan in any trade for Griner increased after an April trade for Marine veteran Trevor Reed did not include him.

Paul Whelan told CNN on Thursday that he is “greatly disappointed that more has not been done” to secure his release.

“I would say that if a message could go to President Biden, that this is a precarious situation that needs to be resolved quickly,” he said in a phone interview. “My bags are packed. I’m ready to go home. I just need an airplane to come and get me.”

As he announced the deal for Griner’s release, Biden pledged that Paul Whelan would not be forgotten.

“Sadly, for totally illegitimate reasons, Russia is treating Paul’s case differently than Brittney’s,” Biden said. “And while we have not yet succeeded at securing Paul’s release, we are not giving up. We will never give up.”

Speaking later at the State Department, Secretary of State Antony Blinken said Russia “continues to insist on sham charges” against Whelan.

“This was not a choice of which American to bring home: The choice was one or none,” Blinken said. “And I wholeheartedly wish that we could have brought Paul home today on the same plane as

WNBA star and two-time Olympic gold medalist Brittney Griner speaks to her lawyers standing in a cage at a courtroom prior to a hearing, in Khimki just outside Moscow, Russia on July 26. Alexander Zemlianichenko via Pool, file

Brittney.”

Numerous Republican lawmakers criticized the deal for leaving Whelan in Russia, including Michigan Rep. Tim Walberg, who said he was heartbroken for the Whelan family.

“They deserve better,” Walberg said in a statement.

David Whelan dismissed criticism that Griner’s celebrity brought about her release and said he hopes Griner’s high profile will continue to bring attention to his brother and other Americans being held overseas.

“We’ve got to support Paul. We’ve got to help him to survive,” David Whelan said. “It’s his mental health I worry about. How do you keep up surviving mentally in that sort of situation? Not only for days, but months and years. We’re coming up on four years, and I think, unfortunately, it may be years more that he has to face.”

Associated Press Writer Matthew Lee in Washington contributed to this report.