(NewsNation) — American journalist Evan Gershkovich was arrested and charged with espionage in Russia. Yet, he’s not the only American wrongfully detained.

Paul Whelan, a U.S. Marine veteran, is serving a 16-year sentence in Russia on espionage charges the U.S. calls politically motivated. He’s been held in Russia since 2018.

David Whelan said his brother has a “valid concern” that he may be left behind again, after negotiations fails to bring home when WNBA all-star Brittney Griner was released in December 2022 after 10 months of detainment.

“I think since we have seen that he has been left behind twice already, that’s a valid concern,” David told NewsNation. “I think he is worried that he is going to have to spend the entire 16 years of his sentence in Russia. I think he’s concerned that he is going to once again go through a process of maybe having some hope of being released and then seeing himself being left behind.”

The U.S. hasn’t said whether or not it will consider a prisoner swap to secure Gershkovich’s release.

U.S. officials have said they don’t have a choice as to which American returns home. Also, with Griner’s case, it wasn’t that officials wanted to leave Paul Whelan or they didn’t fight hard to get him back, but that Griner was released, and he was not.

David Whelan said Russia holds “Americans for extortion purposes.”

“I think the Kremlin is holding Americans for extortion purposes. That’s all. I think that they’re opportunistic,” he said. “I don’t have any question that Ms. Griner came home because that was the only trade that was available to the Americans at the end of last year.”

Yet, he said he thinks the U.S. government needs to figure out how to bring Americans home and “not leave them behind.” He also said he thinks they need to do more in terms of negotiations, especially in light of the war in Ukraine.

“They are getting better at this. The wrongful detention label for Mr. Gershkovich came very, very quickly. That process — it seems to be speeding up. But I think that they do need to escalate either their pressure or their concessions in order to resolve these cases faster as well.”

Gershkovich, a Wall Street Journal reporter, will have the chance to appeal the espionage charges he faces in Russia this month.