Former Soviet military officer and arms trafficking suspect Viktor Bout deplanes after arriving at Westchester County Airport on November 16, 2010 in White Plains, New York.
CNN  — 

Biden administration officials are frustrated that Moscow has yet to respond in a meaningful way to their proposal to return convicted Russian arms trafficker Viktor Bout as part of a deal to secure the release of US citizens Brittney Griner and Paul Whelan from Russia, with the State Department spokesperson acknowledging “this has not moved to the extent we would like.”

“So far, there is no agreement on this issue,” Kremlin spokesperson Dmitry Peskov said Thursday during a conference call with journalists when asked about the offer by the US, which was reported exclusively by CNN on Wednesday.

US Secretary of State Antony Blinken publicly announced that the US had presented Moscow with “a substantial proposal” for the release of Griner and Whelan, but did not provide details about what the proposal contained.

The top US diplomat said that he expected a call with Russian Foreign Minister Sergey Lavrov, telling reporters he hopes that by speaking with Lavrov, “I can advance the efforts to bring them home.”

Although Russia has acknowledged the US request for the call between the two top diplomats, it has yet to be nailed down.

“We continue to go back and forth,” State Department spokesperson Ned Price said at a briefing Thursday. “We continue to expect that they’ll have an opportunity to speak in the coming days.”

The Russian Foreign Ministry said Thursday that Lavrov would “pay attention” to the request for the call with Blinken when “time permits,” but said the foreign minister’s schedule was currently busy.

Biden administration officials have indicated that Moscow has not been responsive to the deal that has been “conveyed repeatedly, directly over the course of several weeks,” in the words of the State Department spokesperson.

“The fact that, now several weeks later, we are where we are, I think you can read into that as being a reflection of the fact that this has not moved to the extent we would like,” Price said Thursday.

National Security Council Strategic Coordinator for Communications John Kirby said Thursday that “a lot” went into the decision to go public with the news that a deal had been presented, saying on ABC’s “Good Morning America” that “ultimately, we came down on the side that it was important to put this out there … the American people know how seriously President Biden takes his responsibilities to bring American citizens home when they’ve been unjustly detained.”

“We also thought it was important for the world to know how seriously America takes that responsibility,” Kirby said.

However, frustration at Russia’s lack of substantive response to the deal was an underlying factor in the administration’s decision to on Wednesday publicize the agreement.

“We communicated a substantial offer that we believe could be successful based on a history of conversations with the Russians,” a senior administration official told CNN Wednesday.

There is acknowledgment within the administration that negotiations to try to free detained Americans are often difficult.

“We start all negotiations to bring home Americans held hostage or wrongfully detained with a bad actor on the other side. We start all of these with somebody who has taken a human being American and treated them as a bargaining chip,” the senior official said.

“So in some ways, it’s not surprising, even if it’s disheartening, when those same actors don’t necessarily respond directly to our offers, don’t engage constructively in negotiations,” they said.

Asked about the proposed prisoner swap Thursday, Russian Foreign Ministry spokesperson Maria Zakharova noted that President Joe Biden and Russian President Vladimir Putin had discussed the matter “some time ago,” and the two sides “have yet to achieve tangible results.”

“We proceed from the premise that the interests of both sides must be taken into consideration during this negotiating process,” she said, according to a transcript of the question and answer from the Foreign Ministry.

Russia has repeatedly raised Bout, who is serving a 25 year prison sentence in the US, as a potential subject for a swap for a number of detained Americans.

CNN reported Wednesday that the potential of trading Bout had been under discussion since earlier this year, and received Biden’s backing, according to sources briefed on the matter.

Biden’s support for the swap overrides opposition from the Department of Justice, which is generally against prisoner trades.

Among senior Biden administration officials, the idea of prisoner swaps gained new momentum earlier this year after the successful release of Trevor Reed, a former Marine who was held captive in Russia for more than two years. Reed was traded for Konstantin Yaroshenko, a Russian pilot then serving a 20-year federal prison sentence for cocaine smuggling conspiracy.

The families of WNBA star Griner, jailed in Moscow for drug possession since February, and Whelan, who has been held by Russia for alleged espionage since 2018, have pleaded with the Biden administration to secure their release, including via a prisoner exchange if necessary.

Griner, who pleaded guilty earlier this month but said she unintentionally brought cannabis into Russia, testified in a Russian courtroom Wednesday as part of her ongoing trial on drug charges, for which she faces up to 10 years in prison. It is understood that her trial will have to conclude prior to a deal being finalized, according to US officials familiar with the Russian judicial process and the inner workings of US-Russia negotiations.

This story and headline have been updated with additional reporting.

CNN’s Evan Perez and Betsy Klein contributed to this report.