Russia and Ukraine on Saturday exchanged 35 prisoners each in a carefully negotiated swap that could signal a thaw in relations. 

The swap — which included high-profile figures like filmmaker Oleg Sentsov and potential MH17 witness Vladimir Tsemakh — was seen as a key step toward resolving the conflict in eastern Ukraine that has claimed more than 13,000 lives since it broke out in 2014. 

an>

Russian President Vladimir Putin and Ukrainian President Volodymyr Zelenskiy made a positive assessment of the swap when discussing it by phone on Saturday and agreed on further contacts, the Kremlin has said. U.S. President Donald Trump congratulated both countries, tweeting Saturday that the move was “perhaps a first giant step to peace.”

Unlike Zelenskiy, whose administration has publicized all 35 people who were released to Ukraine, the Kremlin has declined to list the names of the 35 people that Russia received as part of the exchange. Some of the prisoners given to Russia have been separately confirmed.

Here’s who Russia handed over to Ukraine:

Oleg Sentsov, 43, Ukrainian filmmaker

A native Crimean, Sentsov was sentenced to 20 years in a remote Arctic prison in 2015 after being convicted of terrorism following Russia’s annexation of Crimea in 2014.

Sentsov was detained and accused of plotting terrorist acts in May 2014 alongside three other activists: Gennady Afanasyev, Alexei Chirniy and Alexander Kolchenko. Sentsov said there was no evidence to back up the claims, while Russian human rights activists and much of the West said the charges of terrorism were politically motivated.