TALLINN, Estonia (AP) — New details emerged Friday on the largest prisoner swap since the Cold War, with the Kremlin acknowledging for the first time that some of the Russians held in the West were from its security services. Families of freed dissidents, meanwhile, expressed their joy at the surprise release.

While journalists Evan Gershkovich and Alsu Kurmasheva and former Marine Paul Whelan were greeted by their families and President Joe Biden in Maryland on Thursday night, President Vladimir Putin embraced each of the Russian returnees at Moscow’s Vnukovo Airport, and promised them state awards and a “talk about your future.”

Among the eight returning to Moscow was Vadim Krasikov, a Russian assassin who was serving a life sentence in Germany for the 2019 killing of a former Chechen fighter in a Berlin park. German judges said the murder was carried out on orders from Russian authorities.

Kremlin spokesman Dmitry Peskov told reporters Friday that Krasikov is an officer of the Federal Security Service, or FSB — a fact reported in the West even as Moscow denied any state involvement.

He also said Krasikov once served in the FSB’s special Alpha unit, along with some of Putin’s bodyguards.

“Naturally, they also greeted each other yesterday when they saw each other,” Peskov said, underscoring Putin’s high interest in including Kresikov in the swap.

Peskov also confirmed that the couple released in Slovenia — Artem Dultsov and Anna Dultsova — were undercover intelligence officers commonly known as “illegals.” Posing as Argentine expats, they used Ljubljana as their base since 2017 to relay Moscow’s orders to other sleeper agents and were arrested on espionage charges in 2022.

Their two children joined them as they flew to Moscow via Ankara, Turkey, where the mass exchange took place. They do not speak Russian, and only learned their parents were Russian nationals sometime on the flight, Peskov said.

They also did not know who Putin was, “asking who is it greeting them,” he added.

“That’s how illegals work, and that’s the sacrifices they make because of their dedication to their work,” Peskov said.

Two dozen prisoners were freed in the historic trade, which was in the works for months and unfolded despite relations between Washington and Moscow being at their lowest point since the Cold War after Putin’s February 2022 invasion of Ukraine.

Moscow freed 15 people in the exchange — Americans, Germans and Russian dissidents — most of whom have been jailed on charges widely seen as politically motivated. Another German national was released by Belarus.

Among the dissidents released were Vladimir Kara-Murza, a Kremlin critic and Pulitzer Prize-winning writer serving 25 years on charges of treason widely seen as politically motivated; associates of late opposition leader Alexei Navalny; Oleg Orlov, a veteran human rights campaigner, and Ilya Yashin, imprisoned for criticizing the war in Ukraine.

They were flown to Germany amid an outpouring of joy from their supporters and relatives — but also some shock and surprise.

“God, it is such happiness! I cried so much when I found out. And later, too. And I’m about to cry again now, as well,” said Tatyana Usmanova, the wife of Andrei Pivovarov, another opposition activist released in the swap, writing on Facebook as she flew to meet him. Pivovarov was arrested in 2021 and sentenced to four years in prison.

In a phone call to Biden, Kara-Murza said “no word is strong enough for this.”

“I don’t believe what’s happening. I still think I’m sleeping in my prison cell in (the Siberian city of) Omsk instead of hearing your voice. But I just want you to know that you’ve done a wonderful thing by saving so many people,” he said in a video posted on X.