Ukraine Fighting Pauses, Briefly, for Big Prisoner Exchange 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. 27, 2017 MOSCOW — 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 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. 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. 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.