Brittney Griner updates: WNBA star reunites with wife

Elizabeth Whelan, the sister of ex-Marine Paul Whelan, the U.S. citizen being held in Russia as an alleged spy, told ABC News in an interview Thursday she is happy for Brittney Griner, but also frustrated Paul remains in custody.

"The Russians have been clear with all of these cases that they treat them all separately," Elizabeth Whelan told ABC News. "We try to bundle them together and get everybody out at once. We don't want to leave anyone behind. But that is not necessarily the way our opponents are dealing with this situation."

"We've always known that the Russians were treating Paul separately, and therefore, we always knew that there was a chance that this would happen, that Brittney would be released first," she continued.

U.S. officials said they wanted to exchange Viktor Bout for both Griner and Paul Whelan, but that Russian officials would not engage on both and said either Griner could be swapped for Bout or no one could be swapped.

"I think we need to start dealing with Russia as the entity that it actually is now and not the way we might want it to be," Elizabeth Whelan said. "They talk about Paul being a spy, but they're the ones who set Paul up and created this spy story that is sort of based in a fairy tale [that] has to be undermined. We have to find a way around that."

President Joe Biden delivered the good news about Brittney Griner's release in person directly to her wife, Cherelle, at the White House Thursday morning, according to press secretary Karine Jean-Pierre.

"Cherelle had been invited to the White House for a meeting with the national security adviser Jake Sullivan. When she arrived, she was welcomed into the Oval Office by President Biden, who personally delivered the news that Brittney would be returning home today," Jean-Pierre said.

ABC News' Mary Bruce pressed the White House on any plans Biden has to meet with Griner upon her return to the United States, but Jean-Pierre didn’t have any guidance.

"I don't have anything to preview at this time. Our efforts right now, our focus, is to get her home safely and to get her back to her family, to her team, to her loved ones, and give her all the necessary tools she will need to reengage, to come back to the U.S. in the way that she chooses, right?" Jean-Pierre said.

-ABC News' Molly Nagle

Senators from both side of the aisle celebrated Brittney Griner's freedom from Russian detention Thursday, but several members also questioned the decision to swap Griner for known international arms dealer Viktor Bout.

Sen. Chris Coons, D-Del., told ABC News that while he sees Griner's return as "good news" and a "significant accomplishment by the Biden administration," he's worried about the precedent that could be set for exchanges of high-profile Russian criminals like Bout.

"It was clear over many months that Putin was only going to release Brittney Griner in exchange for this person," Coons said. "And that's the risk, is that the more we engage in such exchanges, the more Americans are at risk of being scooped up and held as leverage to try and secure the release of folks who we would rather not have to release."

Republicans shared Coons' concern.

"I worry about -- this sets in motion, you know, just 'grab an American,'" Sen. Lindsey Graham, R-S.C., said.

"Well, I hate it," Sen. John Cornyn, R-Texas, said when asked about the administration's move to free Bout. "But I think you're left with the decision: yes or no. And like I said, I think I would never be happy to have an American in a Russian penal colony, or under any circumstances, so unfortunately, that's the sort of way Putin does business."

Sen. Roger Marshall, R-Kan., agreed with that assessment.

"We traded a basketball player for a known terrorist criminal," Marshall said, suggesting that the U.S. should have driven a tougher bargain.

-ABC News' Allie Pecorin

Paul Whelan called CNN from prison on Thursday, saying he's "happy that Brittney is going home today and that Trevor [Reed] went home when he did -- but I don't understand why I’m still sitting here."

Whelan said he's "greatly disappointed that more has not been done to secure my release," adding, "I was arrested for a crime that never occurred."

Whelan, who has been imprisoned in Russia for nearly four years, said his message to Biden is: "This is a precarious situation that needs to be resolved quickly, and I would hope that he and his administration would do everything they could to get me home. regardless of the price they may have to pay at this point."

Biden said Thursday that the prisoner swap was "not a choice" between Brittney Griner and Whelan.

"Russia is treating Paul's case differently than Brittney's, and while we have not yet succeeded in securing Paul's release we are not giving up. We will never give up," he said.

"We'll continue to engage the Russians on Paul, and we'll continue to look at everything possible to bring him home," Secretary of State Antony Blinken added.

-ABC News' Ben Gittleson