Fighting this month between the Ukrainian military and Russian-backed separatists

After a sharp escalation in fighting this month between the Ukrainian military and Russian-backed separatists, the two sides took an unusual break from shelling each other on Wednesday to carry out their biggest exchange of prisoners since the conflict began in 2014.

The prisoner swap — involving 73 Ukrainians held captive by the rebels, and more than 200 separatists captured by Ukraine — was carried out without serious incident just days after the Trump administration agreed to provide weapons to Ukraine. That move, Russia says, will only escalate a conflict that has killed more than 10,000 people.

The prompt release of all prisoners was a key part of a 2015 peace agreement brokered by France, Germany and Russia in Minsk, the capital of Belarus. But like many other parts of the Minsk deal, it has gotten bogged down in accusations on each side that the other was not fulfilling its obligations.

The two sides have swapped prisoners on numerous prior occasions, but Wednesday’s exchange was the biggest transfer of captives on a single day, Ukrainian officials said.

The Ukrainian security agency, known as the S.B.U., said on Wednesday that a total of 3,215 Ukrainians captured by the rebels since 2014 had now been released and that 103 remained in captivity in rebel-held territory, with dozens more held prisoner in Russia.

The United States and the European Union have each set full implementation of the Minsk deal as a key condition for the lifting of economic sanctions imposed on Russia over its annexation of Crimea and its support for pro-Russia rebels in the eastern Ukrainian regions of Donetsk and Luhansk.

Russia has insisted that it is not involved in the conflict, despite extensive evidence that has been sending arms, money and soldiers to support the rebel cause. But, tiring of Western sanctions and violent infighting among separatist rebels, Moscow has shown some signs of wanting to dial down a conflict that has cost it diplomatically and economically.

The protracted negotiations over Wednesday’s prisoner swap involved Viktor V. Medvedchuk, a Ukrainian with close ties to Russia’s president, Vladimir V. Putin. The Russian leader, who is up for re-election in March, saw his popularity ratings in Russia soar after he grabbed Crimea but he has garnered no discernible political benefit from Russia’s intervention in eastern Ukraine.

The rebels, an unruly group of feuding gunmen and fervently pro-Russian political operatives, have shown no interest in a long-term settlement that would strip them of Russian support, without which their secession movement would probably crumble. Mr. Putin, anxious about alienating hard-line nationalists in Russia, seems disinclined to cut the rebels loose but faces rapidly diminishing returns from a military venture that has poisoned Moscow’s relations with the West.

Speaking in Vienna earlier this month, at a meeting of the Organization for Security and Cooperation in Europe, whose monitoring mission in eastern Ukraine recently reported a sharp uptick in fighting, the American secretary of state, Rex W. Tillerson, said the conflict “stands as the single most difficult obstacle to us renormalizing the relationship with Russia, which we badly would like to do.”

While Ukraine’s president, Petro O. Poroshenko, rejoiced at the exchange of prisoners and showed up in military fatigues near rebel-held territory to meet the released Ukrainians, the authorities in separatist-held Donetsk responded with accusations that Ukraine had violated its obligations. The Donbass News Agency, a rebel mouthpiece, made a litany of complaints, accusing Ukraine of not blocking certain roads as agreed and not living up to the spirit of the Minsk deal.

Ukraine was originally supposed to return 306 prisoners to rebel-held territory but said that 40 of these had already been released and did not show up for the exchange, carried out at checkpoint near the rebel-held town of Horlivka. A further 29 captives held by Ukraine refused to return to rebel-held territory, Ukrainian officials said.

 

Source: AFP