Russia freed WNBA star Brittney Griner on Thursday in a dramatic high-profile prisoner exchange, with the United States releasing notorious Russian arms dealer Viktor Bout, US and Russian officials said. The swap, at a time of heightened tensions over Ukraine, achieved a key goal for President Joe Biden, but it came at a heavy price – leaving behind an American jailed for nearly four years in Russia.

The deal, the second such exchange in eight months with Russia, secured the release of the most prominent American detained abroad. Griner is a two-time Olympic gold medalist whose months-long incarceration on drug charges brought unprecedented attention to the wrongfully incarcerated population.

Biden’s authorization to free a Russian criminal once nicknamed “the Merchant of Death” underscored the mounting pressure his administration faced to bring Griner home, particularly after the recent resolution of the criminal case her and her subsequent transfer to a penal colony.

The swap was confirmed by US officials with direct knowledge of the negotiations who were not authorized to publicly discuss the deal before a White House announcement and spoke on condition of anonymity. Biden spoke with Griner on the phone Thursday while his wife, Cherelle, was in the Oval Office. The president was due to address reporters later in the morning.

“Moments ago I talked to Brittney Griner. She’s safe. She’s on a plane. She’s on her way home,” Biden tweeted.

The Russian Foreign Ministry also confirmed the exchange, saying in a statement carried by Russian news agencies that the exchange took place in Abu-Dhabi and that Bout was flown home.

Russian and American officials had expressed cautious optimism in recent weeks after months of strained negotiations, with Biden saying in November that he hoped Russia would come to an agreement now that the midterm elections have been completed. A senior Russian official said last week that a deal was possible before the end of the year.

Even so, the fact that the deal was a one-for-one exchange came as a surprise since US officials had for months expressed their determination to bring home both Griner and Paul Whelan, executive of Michigan’s corporate security has been jailed in Russia since December 2018 on espionage charges that his family and the US government say are baseless.

In extraditing Bout, the United States freed a former Soviet Army lieutenant colonel who the Justice Department once described as one of the world’s most prolific arms dealers. Bout, whose exploits inspired a Hollywood movie, was serving a 25-year sentence on charges that he conspired to sell tens of millions of dollars in weapons that US officials said were to be used against Americans.

The Biden administration was ultimately willing to trade Bout if it meant Griner’s freedom. The detention of one of the greatest players in WNBA history has contributed to an unprecedented turn of public attention for an individual detainee case – not to mention intense pressure on the White House.

Griner’s arrest in February made her the most high-profile American imprisoned abroad. Her status as an openly gay Black woman, closeted in a country where the authorities were hostile to the LBGTQ community, injected racial, gender and social dynamics into her legal saga and made each development a matter of international importance .

Her case not only brought unprecedented publicity to the dozens of Americans wrongfully detained by foreign governments, but also emerged as a major turning point in US-Russian diplomacy at a time of deteriorating relations sparked by Moscow’s war against Ukraine.

The exchange took place despite relations between the powers deteriorating. But the imprisonment of the Americans produced a rare diplomatic opening, leading to the highest known contact between Washington and Moscow – a phone call between Secretary of State Antony Blinken and Russian Foreign Minister Sergey Lavrov – in ‘more than five months.

In an extraordinary move during otherwise secret negotiations, Blinken publicly disclosed in July that the United States had made a “substantial offer” to Russia for Griner and Whelan. Although she did not specify the terms, people familiar with her said the United States had offered Bout.

Such a public overture drew a barrage of rebuke from the Russians, who said they preferred to settle such cases in private, and risked weakening the US government’s negotiating hand for this and future deals by administration seems too desperate. But the announcement was also intended to communicate to the public that Biden was doing what he could and to ensure pressure on the Russians.

In addition to the efforts of US officials, the release also followed months of backchannel negotiations involving Bill Richardson, the former US ambassador to the United Nations and a frequent emissary in hostage talks, and the chief deputy his Mickey Bergman. The men had made several trips abroad in the past year to discuss exchange scenarios with Russian contacts.

Griner was arrested at Moscow’s Sheremetyevo airport in February when customs officials said they found vape canisters with cannabis oil in her luggage. She pleaded guilty in July, although she still faces trial because admitting guilt in Russia’s judicial system does not automatically end a case.

She acknowledged in court that she had the canisters, but said that she had no criminal intent and said that their presence in her luggage was due to hasty packing.

Before she was sentenced on Aug. 4 and received a sentence that her attorneys said was disproportionate to the crime, an emotional Griner apologized “for my mistake and the embarrassment I caused them.” She added: “I hope that your decision will not end my life.”

Her supporters were largely quiet for weeks after her arrest, but that approach changed in May once the State Department designated her as illegally detained. A separate trade, Marine veteran Trevor Reed for Konstantin Yaroshenko, a Russian pilot convicted in the United States in a cocaine-trafficking conspiracy, spurred hope that additional such exchanges may be in the works.

Whelan has been held in Russia since December 2018. The US government has also classified him as wrongfully detained. He was sentenced in 2020 to 16 years in prison.

Whelan was not included in Reed’s prisoner swap, increasing pressure on the Biden administration to make sure any deal that brought Griner home included him as well.