Ukrainian orphans Ivan and Maksym, 17 and 16, escaped shelling and hunger in besieged Mariupol only to be captured and taken to the Russian-occupied city of Donetsk where they were held incommunicado for months with dozens of other children.

They are among about 400 Ukrainian children to have returned from Russia or Russian-held territory since Moscow invaded Ukraine – a fraction of the 20,000 children that Kyiv has identified as taken without the consent.

The boys and four other Ukrainian children told their stories in The Hague, where the campaign “Bring Kids Back UA” was launched in September by Netherlands-based NGO Orphans Feeding Foundation.

The boys, students at the Mariupol Technical School of Building, were living in a dormitory when the area came under fierce bombardment by Russian forces. Food and water ran out, and they fled on foot in March to a nearby village.

“When we arrived, we went to the hospital, because there was nowhere else to go. We said we were orphans, and they informed the Donetsk hospital. Then child protection services came and asked where our parents were. So we were taken away,” Maksym told Reuters.

Ivan said: “We didn’t want to go there, but we didn’t have a choice. We were fed four times a week. We spent time in our rooms and played on our phones. They let us go outside for one hour a day, and not every day. There was nothing for us to do.”

Moscow has repeatedly denied forcibly taking Ukrainian children, saying it found only a small number of children in orphanages or without parental care, and tried to accommodate as many as possible with relatives in Russia.

The International Criminal Court issued an arrest warrant in March against Russian president Vladimir Putin, accusing him of the war crime of illegally deporting hundreds of children from Ukraine.