The prisoner swap that resulted in Brittney Griner’s release has been in the works since at least Nov. 29, when the U.S. government requested the removal of Viktor Bout from USP Marion in Marion, Illinois, according to a court document unsealed Thursday.

The document, signed by George Turner, assistant United States attorney from the Southern District of New York, requested the Bureau of Prisons allow U.S. Marshals to take custody of Bout sometime between Dec. 2 and Dec. 16.

The move was “based on the significant foreign policy interests of the United States,” the document said, but did not mention Griner or a prisoner exchange.

The government expended significant resources and time to bring Bout to justice, but a source familiar with the prosecution of Bout said they recognized the "competing interests" that resulted in his release from U.S. custody.

Whether Bout represents a future threat, this source said that while Bout is not old he has been "out of the game," which would impede his ability to go back to his former operations. However, the source called Bout a "shrewd operator" with "a lot of friends" in Russian military and intelligence circles.

-ABC News' Aaron Katersky

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