(WASHINGTON) -- The Biden administration's unusual decision to publicize its offer to Russia to free Brittney Griner and Paul Whelan -- the basketball star and former Marine whom the U.S. says are wrongfully held by Moscow -- was made in part to reassure Americans rather than entice the Russians, White House aides said Thursday.
White House spokesman John Kirby said on Good Morning America that the deal the U.S. proposed for Griner and Whelan had been "set forth many weeks ago" and that the administration decided to publicize it to show Americans what President Joe Biden was doing to try to free them amid months-long scrutiny.
"This isn't something that just happened ... This has been going on for a while, and we just haven't been able to come to fruition on it," Kirby said.
"There was a lot" that went into the U.S. decision to reveal the proposed deal, he said, "both in terms of what was happening, what wasn't happening and certainly in the context of Mrs. Griner having to testify yesterday."
Kirby attested to the administration's investment, amid criticism from some quarters that they weren't more engaged. Highlighting the offer to Russia now was valuable even if it hadn't been accepted, Kirby insisted.
"It was important to put this out there, that the American people know how seriously President Biden takes his responsibilities to bring American citizens home when they've been unjustly detained, but we also thought it was important for the world to know how seriously America takes that responsibility," he said.
Griner was arrested and later pleaded to illegally bringing hashish oil into the country, though she said it was "inadvertent" and was part of her vape cartridge. Her court case is expected to go into next month.
Whelan, who worked in corporate security after being discharged from the Marines, was convicted in Russia of espionage -- which he and the U.S. deny.
Sources confirmed to ABC News on Wednesday that the possible deal, which the State Department described to reporters as a "substantial proposal," included exchanging convicted arms dealer Viktor Bout for Griner and Whelan.
Bout, dubbed the "Merchant of Death" by the media, was an internationally infamous weapons trafficker before his 2008 arrest in Thailand. He is serving a 25-year sentence.
State Department spokesman Ned Price declined on Wednesday to shed much light on the government's offer to Russia but he acknowledged there was precedent for prisoner trades.
Often, however, such deals only become public once they are confirmed and in motion.
"We demonstrated with [Marine veteran] Trevor Reed, who came home some months ago, that the president is prepared to make tough decisions if it means the safe return of Americans," Blinken told reporters, referring to the former Marine jailed in Russia before he was exchanged for Konstantin Yaroshenko, who was serving a 20-year sentence in the U.S. for drug smuggling.
Reed has publicly urged the White House to do more for Griner and Whelan.
He felt the administration was "not doing enough," he told ABC News earlier this month.
"I hope that President Biden and his administration will do everything possible to get both, you know, Brittney and Paul out of Russia, and that they will do that immediately," Reed said then. "Because every day that, you know, they sit here and wait to make a decision is one more day that, you know, Paul and Brittney are suffering."
Both Whelan's family and Griner's attorneys said they were gladdened by news on Wednesday of a potential deal for their freedom -- but also noted the future was unknown.
"The offer that the U.S. government has made, and extraordinarily made public, is super. Hopefully the Russian government will take the concessions that have been made and allow Paul to come home," Paul Whelan's twin brother, David Whelan, said Thursday on Good Morning America.
An attorney for Griner, Maria Blagovolina, said the "defense team learned about [the] U.S. offer from the news" and "is not participating in the swap discussions. From the legal perspective, the swap is possible only after the court reaches a verdict. In any case, we would be really happy if Brittney will be able to come home and hope it will be soon."
At a press conference in Moscow on Thursday, Russian Ministry of Foreign Affairs spokeswoman Maria Vladimirovna Zakharova confirmed that "the issue of mutual exchange of Russian and American citizens, staying in places of detention on the territory of the two countries, was discussed at one time by the presidents of Russia and the United States," but "a concrete result has not yet been achieved."
Meanwhile, Kremlin spokesman Dmitry Peskov told reporters Thursday that "there are no agreements in this area yet."
ABC News' Anastasia Bagaeva, Shannon K. Crawford and Ben Gittleson contributed to this report.