A high-profile prisoner swap between Russia and Ukraine was underway on Saturday, officials from both countries confirmed.

Planes each carrying a reported 35 prisoners landed almost simultaneously at Vnukovo airport in Moscow and at Kyiv's Boryspil airport.

In the Ukrainian capital, relatives of the prisoners were seen waving and applauding on the tarmac. President Volodymyr Zelenskiy greeted the prisoners as they stepped down the stairway.

Two Ukrainian presidency officials and Kremlin Press Secretary Dmitry Peskov confirmed the prisoner exchange.

Zelenskiy praised the swap as a "first step" towards ending the war. "We have to take all the steps to finish this horrible war," he said, pledging to also return "our territory."

Reactions from world leaders

German Chancellor Angela Merkel said the release of the prisoners was a "sign of hope" and added that "it's worth continuing the hard work to implement the Minsk Agreement."

French Foreign Minister Jean-Yves Le Drian said that "France, alongside Germany, will support efforts by both sides with the aim of making concrete new advances in the coming weeks."

US President Donald Trump tweeted that the move was "very good news, perhaps a first giant step to peace."

While most of the prisoners appeared to be in good physical condition, one prisoner struggled down the steps with crutches while another had to be supported by the arms.

Thirty-five prisoners are reportedly being released by each side. Both Russia and Ukraine have been tight-lipped regarding the identities of the prisoners.

Ukrainian filmmaker Oleg Sentsov, one of the prisoners confirmed to have been released, said "I thank all the people who have fought for us."

Read more: Ukraine parliament appoints 35-year-old lawyer as new prime minister

Relatives of the Ukrainian prisoners applauded the plane's arrival in Kyiv

Prisoners reportedly released from Russia

Oleg Sentsov, a filmmaker convicted by Moscow in 2015 of planning "terrorist attacks" in Moscow-annexed Crimea and who was serving a 20-year jail sentence in Russia.

Up to 24 sailors apprehended in November 2018 by the Russian coast guard after attempting to pass from the Black Sea into the Sea of Azov.

Activists who had been with the sailors including Mykola Karpyuk, Volodymyr Balukh and Pavlo Hryb.

Roman Sushchenko, the Paris correspondent for Ukraine's Ukrinform national news agency, imprisoned for spying.

Two agents of Ukraine's SBU security service, captured by Russia in 2018.

Pavlo Gryb, a 21-year-old blogger and the youngest of the prisoners, sentenced to six years' prison for allegedly inciting a friend to carry out a bombing.

Stanislav Klykh, a history professor.

Mykola Karpyuk, a senior member of two Ukrainian nationalist protest groups.

Ukrainian filmmaker and activist Oleg Sentsov is one of the prisoners freed in the exchange

Prisoners reportedly released from Ukraine

Vladimir Tsemakh, air-defense specialist for pro-Russian separatists, released this week from detention and believed to have been a key witness in the 2014 downing of flight MH17.

Kyrylo Vyshynsky, a journalist for state news agency RIA Novosti, released on bail in August pending trial for "high treason."

Read more: German foreign minister urges Russia, Ukraine to revive peace talks

Leading up to the swap

The swap was the first major exchange of prisoners between Russia and Ukraine since the crisis in Crimea broke out in 2014. Russia annexed Ukraine's Crimean Peninsula and insurgents destabilized eastern Ukraine.

More than 13,000 people have been killed in the conflict in the Donetsk and Luhansk regions. Relations between the two neighboring countries have since deteriorated.

The Republic of Crimea, officially part of Ukraine, lies on a peninsula and is separated from Russia to the east by the Kerch Strait

President Zelenskiy raised the prospect of a prisoner swap after his election in May and called for the revival of peace efforts between the two nations. He will meet with leaders from Russia, Germany and France later this month.

Russian President Vladimir Putin said on Thursday that the "large-scale" prisoner exchange with Ukraine was being finalized. He added that the swap would be "a huge step towards normalizing relations" following Zelenskiy's rise to power in May.

Putin added that Moscow found it difficult to agree to the names Ukraine had nominated for the exchange.

Read more: Russia and Ukraine free prisoners in latest swap

Netherlands pleads with Ukraine over Tsemakh

Dutch prosecutors urged Ukraine not to allow Tsemakh to travel to Russia, fearing his release could jeopardize flight MH17 investigations.

The Dutch government contacted Kyiv "several times and at the very highest level" in a failed attempt to prevent the handover of Tsemakh. Dutch Foreign Minister Stef Blok said in a letter to parliament that he "regretted" Kyiv's decision.

In July 2014, a Russian-made missile shot down MH17 over eastern Ukraine, killing all 283 people on board.

mvb/aw (AFP, AP, Reuters)

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