Russia and Ukraine exchanged hundreds more prisoners Saturday as part of a major swap that amounted to a rare moment of cooperation in otherwise failed efforts to reach a ceasefire.

As Kyiv completed its largest prisoner exchange of the war on May 25, exchanging 1,000 Ukrainian POWs for 1,000 Russians, some spoke out on social media to criticize authorities for failing to return certain captives.

The third day of prisoner exchanges between Russia and Ukraine went ahead as planned on Sunday, wrapping up a program agreed to earlier this month, hours after a second night of deadly missile and drone strikes across much of Ukraine.