Kozatske, Kostya's village in the Kherson region, was occupied at the very beginning of Russia's full-scale invasion of Ukraine in February 2022. But things got even worse for the 14-year-old, who at the time was living with his older sisters and a sick father in need of care.

One day, when Kostya went off to get help, the rest of his family was evacuated to Nova Kakhovka, a territory Russia occupied but where no fighting was going on. 

"When I came back, they were gone. There was probably no more room on the bus," he said. "I don't know why they didn't come to get me, I was a bit disappointed about that."

After a few months of living alone, he was offered the chance to go to a Russian camp in Anapa on Russia's Black Sea coast. It's from this camp that children were relocated and placed in families in other parts of Russia and Russian-occupied Ukraine.

Kostya is one of 19,500 children who, according to the Ukrainian authorities, were illegally deported to Russia and the Russian-occupied territories of Ukraine.

Daria Herasymchuk, Ukraine's commissioner for children's rights and child rehabilitation, told DW this figure included children who had left with their parents. She said several families had been forced to take this step because of Russia's invasion. In March 2023, the International Criminal Court in The Hague issued an arrest warrant for Russian President Vladimir Putin and his commissioner for children's rights, Maria Lvova-Belova, after the two were accused of war crimes, including the deportation of children.

'Get me out'

Kostya said he was told in Anapa that he would be sent to a home if his family did not come to get him. Eventually, he was able to get in touch with his sister.

"I told her to do something and get me out," he said. But she couldn't do anything, mainly because she was still a minor at the time.

Not long after, authorities told him that adoptive parents had been found for him near Anapa. Though he was not looking for a new family, he agreed to go.

"I've never seen such happy parents," he said. They had moved to Russia after the Russian occupation of the Donbas in 2014 and had presumably received Russian citizenship. "They said that they were Ukrainians. They had the Ukrainian flag and coat of arms, but also the Russian coat of arms because they are in Russia, after all."

Kostya was their third adopted child.

Adoptive parents mainly military, teachers

According to Dmytro Lubinets, Ukraine's ombudsman for human rights, around 400 children have been adopted by Russian families. The best-known case is a girl taken from an orphanage in Kherson. Journalists found out she had been adopted by Russian politician Sergey Mironov and his wife.

The Regional Center for Human Rights has been able to track at least 378 deported Ukrainian children. Kateryna Rashevska, a legal expert with the Kyiv-based NGO, explained that Russia legally viewed adopted children as the biological children of their adoptive parents rather than children in the care of a guardian. 

"Parents can change the first and last name, place and date of birth within six months," she said.

The NGO has uncovered the names of some 70 adoptive parents, almost all of whom have adopted several children. Rashevska said most were teachers or in the military, including people who fought in the Chechen wars. But some people worked in the cultural sector, or were representatives of the church or employees in NGOs and foundations.

DW spoke with Vladimir (not his real name — Editor's note), the guardian of Maksym (not his real name). They live in the Moscow region, where Maksym was brought with other orphans from the so-called "Donetsk People's Republic" to the Russian city of Kursk two days before Russia invaded Ukraine in February 2022. He immediately received Russian citizenship, which Vladimir said helped him receive free medical care.

Before going to Russia, Maksym attended a boarding school in Russian-occupied Donetsk and did not know his biological parents. Vladimir told DW that Maksym had initially spoken negatively about Ukraine and Ukrainians. He had said he would return to Donetsk as an adult.

Vladimir said he and his family were against Russia's invasion of Ukraine and that he had explained to Maksym how Russia had attacked Ukraine and not the other way around. "We always emphasize the dignity of the Ukrainian nation and its right to independence. All our children know our position, and so does he."

'You're Russian, speak Russian!'

This attitude seems to be the exception. Lubinets said most children who were deported to Russia were likely to receive a reeducation in their new families.

"They are told: 'You're Russian, speak Russian! Forget everything that happened before and start a new life. You'll go to school and get Russian papers. You'll be brought up as a true Russian and you should be grateful that we saved you,'" he said. 

Lubinets said the rights of Ukrainian children were being violated, particularly their freedom of movement and the right to speak their mother tongue.

Vladimir said he was not afraid of the responsibility of raising Maksym. "If an international court were to declare me guilty, I would stand by this. But my conscience is clear because I do not have belligerent and aggressive motives. We just want to help the child in his situation."

But for Rashevska from the Regional Center for Human Rights in Kyiv, placing children in Russian families is a crime. She said the UN has prohibited the adoption of children by parties in a conflict. Moreover, she pointed out that children should be raised by representatives of the same cultural and ethnic group.

"The adoption itself can probably be categorized as genocide," she added.

However, she does not blame the guardians themselves. She said  Russian authorities were responsible and had created a system of rewards for families who took in Ukrainian children.

She also blamed Putin and Lvova-Belova, as well as children's commissioners in the Russian-occupied territories of Ukraine.

Return to Ukraine

In the end, Kostya spent less than a month with the family near Anapa. After his sister came of age, she contacted him and said he could return to Ukraine. He refused at first, saying he had settled into his new life, but then he changed his mind.

"I hesitated because we were intimidated," he said. "I thought there would be nothing to eat in Ukraine. In Russia, I was promised everything."

When he spoke to his adoptive parents, they told him the decision was his but advised him to stay. "They even suggested my whole family should move," he remembered. Finally, he decided to return because he wanted to see his relatives.

"When I saw the Ukrainian flag and the Ukrainian coat of arms at the border, I immediately had the feeling that I had come back to my country," he said. At first, he stayed at a shelter in Kyiv run by the NGO Save Ukraine, which helps to repatriate children who were deported to Russia and looks after them. Then he spent several months with his family, but eventually returned to the shelter before moving in with a foster family in Poltava. He said he has no regrets about returning to Ukraine.

Difficult to bring back orphans

Almost 400 children have returned to Ukraine so far, according to Ukrainian sources. The proceedings, in which several parties are involved, have been kept secret.

Not all the children who were deported were placed in Russian families. However, at least three children were removed from their families. This is particularly difficult, but it is even harder to bring back orphans who do not have families to raise them. 

Vladimir, who took in Maksym, said it was wrong that some Ukrainian children who had relatives in their home country had been brought to Russia. But he added that whether Maksym should return to Kyiv-controlled Ukrainian territory was "a very difficult question." He said he was worried about the boy's psychological health, saying he had been brainwashed at his boarding school in Donetsk that Ukraine was the "enemy."

The head of Save Ukraine, Mykola Kuleba, said all children should be returned from Russia and told the truth, but he admitted that this was a controversial matter.

"For us as a state, the case remains that these are Ukrainian children," said Lubinets. He said families should decide where a child should live and in cases where children did not have family to decide, Ukrainian authorities should make the decision.

"If a person is 18 years old, it is enough for us to hear that he or she is satisfied, considers himself or herself a citizen of Russia and wants to stay there," said Lubinets. "But I know that many adults will say that they want to return to Ukraine."

This article was originally written in Russian.