The Ukrainian government and Russian-backed separatist forces swapped prisoners in the country's war-ravaged east Sunday in the latest sign of efforts to ease tensions between the warring sides.

Ukrainian President Volodymyr Zelenskiy and Russian President Vladimir Putin agreed on the exchange during peace talks in Paris this month. The negotiations did not result in a peace deal to end the deadly five-year military conflict, but the two parties committed to further talks and a prisoner exchange before the year was out.

Ukraine said 76 of its prisoners were returned, while media reports suggested that Kyiv released 123 prisoners to the rebels. The SBU, Ukraine's security service, said that 12 of those who were returned were service members and that the 64 others were civilians.

"This exchange is proof of how important it is for Ukraine's president to protect every Ukrainian who is in difficult circumstances because of Russian aggression," SBU Chairman Ivan Bakanov said in a statement.

Released prisoners eat cake after they were exchanged in a swap at the Mayorsk crossing point in eastern Ukraine on Sunday, Dec. 29, 2019. Ukrainian Presidential Press Service / via Reuters

Armed troops from both sides looked on as buses arrived Sunday morning at the swap site, a checkpoint near the industrial town of Horlivka in the Donetsk region.

Photos shared in Ukrainian media showed prisoners' being loaded on and off buses, with some being greeted by their loved ones. Others were handed hot drinks and slices of cake to celebrate their release.

The last major prisoner exchange between separatist rebels and Ukrainian forces took place in December 2017, when 233 rebels were exchanged for 73 Ukrainians.

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Sunday's swap comes several months after a direct prisoner exchange between Ukraine and Russia in September. That time, 24 Ukrainian sailors detained by Russia in a naval confrontation in late 2018 were freed, among others.

The swap was considered a major victory for Zelenskiy, who made the return of the sailors one of his election promises.

Zelenskiy, who was a comedian with no political experience before he took office this year, was thrust into the international spotlight following a phone conversation with President Donald Trump in July. The call has become the focal point of an impeachment inquiry in the United States that will see Trump face a Senate trial after having been impeached by the House this month.

The saga, which has dominated Washington politics, has been a distraction for Zelenskiy as he juggles peace negotiations with efforts to revive the country's struggling economy and tackle rampant corruption.

Eastern Ukraine has been ravaged by years of war between government forces and separatists backed by Russia, which were sparked in the aftermath of the 2014 mass protests in Kyiv. The talks in Paris this month renewed hopes for a resolution to the conflict, which has killed more than 13,000 people.

The United States has backed Ukraine throughout the conflict, fearing Putin's efforts to extend Moscow's geopolitical influence. It has also heavily sanctioned Russia for its military intervention and its annexation of Crimea.

Soldiers stand guard before the exchange of prisoners near the Mayorsk crossing point in Ukraine on Sunday. Alexander Ermochenko / Reuters

The U.S. Embassy in Kyiv welcomed the prisoner swap.

"Recognizing that Russia's ongoing aggression confronts Ukraine's leadership with difficult choices, we stand in solidarity with our Ukrainian partners and the many Ukrainians who remain in captivity in Russia and Crimea," the embassy said in a statement.

Trump's decision to put a temporary hold on U.S. military aid, a central issue in the impeachment process, has raised concerns that it could undermine Ukraine's efforts to contain Russian aggression.

Zelenskiy campaigned on ending the conflict, which has continued even though a cease-fire was signed in 2015. He has taken a number of steps toward peace since coming into power, culminating in his talks with Putin in Paris.

He has faced some opposition at home for what some have called "capitulation" to Russia. However, a recent poll showed that 75 percent of Ukrainians support his talks with Putin.