Russia and Ukraine began a major prisoner exchange, swapping hundreds of soldiers and civilians in the first phase of an exchange that was a moment of cooperation in otherwise failed efforts to reach a ceasefire in the 3-year-old war.

Russia and Ukraine agreed to a new prisoner exchange after their delegates met for a second round of renewed peace talks in Istanbul on Monday, but there was no sign the warring sides were any closer to reaching a ceasefire deal than they were when direct negotiations were restarted a month ago.