Ukraine has about 7,000 unclaimed Russian corpses in morgues and refrigerated rail cars, according to Oleksiy Arestovych, adviser to the head of Ukraine’s presidential administration. He said his government’s figure of 18,600 Russian dead was based on Ukrainian reports from the battlefield and intercepted Russian military communications.

Ukraine tried to return the bodies of 3,000 Russian service members on the third day of the war, he said. “They said, ‘We don’t believe in such quantities. We don’t have this number. We’re not ready to accept them.’ ” Ukraine proposed an exchange several times, he said, but “they won’t discuss this at all yet."