KYIV, Ukraine — Mykola Kuleba looked stressed.
The CEO of Save Ukraine listened carefully to his lead investigator whispering into his ear. He covered the microphone on his jacket.
"It’s a very emotionally stressful day because we have our seventh rescue mission and we have a huge problem," said the head of the Ukrainian nongovernmental organization at the start of an interview with NBC News earlier this year.
Save Ukraine’s seventh rescue mission, Kuleba said, was a group of Ukrainian mothers, grandmothers and other legal guardians of Ukrainian children who had been illegally deported and forcibly transferred to Russia and Russian-occupied Ukrainian territories.
With Save Ukraine’s training, planning and funding, these women were traveling through Poland, Belarus and Russia to find their children — a daring, 3,000-mile journey to the other side of the front line.
But it wasn’t going to plan.
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"The FSB tried to block everything," Kuleba said, referring to the Russian security services. "They imprisoned several of our mothers. One was deported and just now, my team met her on the border."
The family was one of hundreds of thousands that the Ukrainians say have been torn apart deliberately by the Russian government, which faces allegations of war crimes.
Kuleba has worked in child protection for decades; before joining Save Ukraine, Kuleba held the post of ombudsman for children with the president of Ukraine for seven years. At the NGO level, he readily admits they’re more nimble than the Ukrainian government.
"We can do things that governments simply can’t,” he told NBC News, without elaborating. But there was a hint of frustration that more than a year into this war, there wasn’t more collaboration with major international organizations or the Ukrainian government.
As Kuleba spoke, a Ukrainian woman named Oksana Stetsenko was on a train from Moscow to Rostov in southwestern Russia. Stetsenko had joined the seventh rescue mission to find her 12-year-old son, Nikita, whom she hadn’t seen in eight long months.
On Sept. 1, 2022, Stetsenko sent Nikita to a boarding school in the occupied village of Kupyansk, about an hour outside of Ukraine’s easternmost city, Kharkiv. She said later, she figured it was safer than her home village of Pischane, deeper into Russian-occupied eastern Ukraine.
“If only I had known,” she said, not finishing her sentence.
A week later, on Sept. 8, Russian troops took Nikita and 12 classmates from the basement of the Kupyansk Special School, loaded them onto trucks and transferred them to Svatove, in Russian-occupied Luhansk.
Two days later, Kupyansk was retaken by Ukrainian troops in a sweeping counteroffensive, but by then, the school was empty. Around that same time, satellite imagery shows the bridge between Stetsenko’s village of Pischane and Kupyansk had been blown up, destroying the only route she could take.
She cried so much after going to bed that her pillow was soaked with tears every night.
“I didn’t know what to think. What else could I think?” she said. She tried to remember what was going through her head, but it was all hard, she said.
“If you had children, you would understand me. It was hard for the soul. This uncertainty, this pit,” Stetsenko said.
Russia maintains that children it has removed from Ukraine were being evacuated and saved from danger.
"Children are sacred,” Russian President Vladimir Putin said in June. “We took them out of the conflict zone, saving their lives and health. That’s what happened.”
On Sept. 11, 2022, a pro-Russian Telegram channel posted a video announcing the “safe evacuation” of 13 children from a school in Kupyansk to Svatove. By Sept. 14, according to Maria Lvova-Belova, Russia’s children’s rights commissioner, the group had been moved again deeper into Luhansk.
Lvova-Belova told NBC News that the group of 13 students had been "taken out from under shelling" and transferred to the Perevalsk Special Correctional Boarding School on Sept. 14.
Stetsenko had no idea what had happened to her son. She said she spent the next month hunkered down in the basement in Pischane, praying at night before evacuating to Kharkiv at the end of October 2022.
Back in June, Ukrainian President Volodymyr Zelenskyy estimated that more than 200,000 children have been deported to Russia or a Russian-occupied territory since Putin’s invasion began in February 2022. That number could be as high as 300,000, according to the Ukrainian president’s adviser on child rights, Daria Herasymchuk.
For Lvova-Belova’s part, she put the number at 700,000 since the war began in 2014, but Ukrainian officials say she hasn’t offered a comprehensive list of names for them to confirm that number.
Back in March, the International Criminal Court issued an arrest warrant for both Lvova-Belova and Putin, accusing them of the "unlawful deportation and transfer of Ukrainian children," which is a war crime. Their actions, according to a statement from Prosecutor Karim Khan, "demonstrate an intention to permanently remove these children from their own country."
Kremlin spokesman Dmitry Peskov called the ICC allegations "outrageous and unacceptable," but noted that Russia does not recognize the court’s jurisdiction.
"And accordingly, any decisions of this kind are null and void for the Russian Federation from the point of view of law," he said March 17.
Since March, Kuleba said, it has proved harder to return Ukrainian children.
"Russians understand now that each case is valued for the ICC," Kuleba said. "Each case is evidence of a war crime."
Ukrainian officials say their real fear, for children like Nikita, is the indoctrination, the so-called Russification they endure after being taken by Russian forces. Nikita described singing the Russian national anthem, dressing in Russian uniforms and being taught a Russian curriculum.
Dmytro Lubinets, the Ukrainian ombudsman for human rights charged with leading the daunting reunification process, explained the playbook, as seen from Kyiv.
"Deport these children to [the] Russian side,” he said in an English-language interview with NBC News in late May. “Take away their Ukrainian documents. Give them Russian documents. [Tell them] … ‘Look, you were never Ukrainians because Ukraine never existed like a state. The Ukrainian nation never existed like a nation. You [were] all the time Russian.’”
Ukrainian officials say they track the number of children returning to the best of their ability. They currently estimate at least 386 Ukrainian children have returned home since the start of the war, all without Russian help. Kuleba’s organization, Save Ukraine, says they are responsible for 176 of those children. Last week, Kuleba reported 13 more Ukrainian children returned home as part of the organization’s 11th rescue mission.
Save Ukraine’s methods are kept under wraps for security, and Kuleba spoke of the operational details in broad brush strokes.
"We provide trainings, because it is very dangerous to go [to Russia] and they [have] to be prepared for interrogation of FSB," Kuleba said.
Stetsenko had never been out of the country before. She had never flown on a plane. And with few resources from a small eastern Ukrainian village, she had no idea there were even organizations that did this.
Within a month of connecting with Save Ukraine, Stetsenko was in Kyiv with the other mothers. And within days, she was on her first-ever flight.
On May 19, Stetsenko hugged Nikita for the first time in eight months.