Kateryna Fedosenko barely looks up from her phone as she paces back and forth, switching between encrypted text and voice notes.
From the Ukrainian capital Kyiv, she's coordinating an urgent rescue mission: getting a group of teenage boys out of Russian-controlled territory.
She glances up briefly. "It will be four boys tomorrow," she says.
Seventeen-year-old Bogdan left his village near the frontline in the Russian-occupied Kherson region three days ago with the teens and two foster parents.
It's a race against time for Kateryna and her team of rescuers at NGO Save Ukraine to extract the boys, who could be drafted into Russia's war machine at any moment.
"The Russian military can come and just take them away. They constantly live in such fear," she says.
Tens of thousands of Ukrainian kids have been stolen — abducted, forcibly transferred, or deported against their will — since the war began in February 2022.
The Ukrainian government has verified the identities of 20,651 children it says have been taken by Russia but estimates the true number to be much higher.
Kateryna is the linchpin of Save Ukraine's rescue operations and, so far, the organisation has brought home more than 1,700 children from Russia and occupied territories.
In the early days of the war, most of their cases were children who'd been abducted, but Kateryna's team is being called to save kids like Bogdan, who are facing new threats growing up under Russian occupation.
There are 1.6 million Ukrainian kids living under Russian control along Ukraine's eastern flank, where indoctrination and military training are being carried out on a mass scale.
Autumn in Russian territory means a conscription drive is fast approaching.
Moscow has installed its own people to run the cities and towns it now occupies and makes life almost impossible for Ukrainians who refuse to accept Russian citizenship and military training.
Boys on the cusp of turning 18 are fair game, adding to the urgency of their escape.
"They draft the boys, force them to sign a contract, and send them to war," Kateryna says.
With the frontline stretching along the eastern and northern borders of the country, the only safe route back into Ukraine is travelling through Russia and its close ally Belarus.
It's a journey of more than a thousand kilometres.
Save Ukraine says Russian border agents, and those planted at Belarusian checkpoints, look for any opportunity to prevent Ukrainians from leaving.
The fear of being detained or interrogated at the border is the reason why many don't attempt the crossing, or take years to try.
Kateryna coordinates a covert network of underground operatives and safe houses across Russia and occupied territory.
As conditions have become more perilous, the team must now engineer the rescues remotely, which means many kids make the crossing alone.
Those leaving have to delete any evidence of communication with Save Ukraine to avoid discovery at one of the many checkpoints along the way.
"If they find out at the border that they are being helped … for them, it would be very harsh," she says.
"They might not let them through because our organisation is seen in Russia as extremist."
As time goes by, the children become harder to track.
Russia constantly moves them to make them more difficult to find.
The team at Save Ukraine uses open-source information such as satellite imagery, flight tracking data, social media pages and posts by the Russian government to track the children.
Among some of the information they've uncovered are the profiles of hundreds of Ukrainian kids on Russian adoption websites.
The children are advertised by age, gender, hair and eye colour.
Even their temperament, personality type and whether they follow instructions are listed.
Anyone scrolling the website can arrange a video call with them.
While we're at Save Ukraine HQ, Valentina comes looking for an update on her little sister Vlada, who was taken four years ago from a summer camp in Russian-annexed Crimea.
Vlada has slowly cut communication with Valentina, who fears she's being brainwashed.
"It seems like a foster family took her," she says. "She called me, and then she just disappeared. After that, she deleted the entire chat history … Then she blocked all her social media."
In 2023, Vlada's grandmother went to Crimea to pick her up, where she was interrogated by Russian security agents for 14 hours.
"Grandma didn't make it," says Valentina.
She wells up as she recalls last hearing from Vlada in 2025, when she told her she planned to move to Moscow with her new Russian family.
"I don't want her to be there. I want everyone to be close by," Valentina says. "We fought, but still, whatever kind of sister she was, she's my sister."
Russia has targeted some of Ukraine's most vulnerable — orphans, children with disabilities and those from impoverished families — knowing they will be harder to trace.
It said it was temporarily removing the children for their own safety.
The first sign of Moscow's intentions to abduct Ukrainian children on a mass scale came just weeks after the war broke out, when President Vladimir Putin met with his Children's Commissioner, Maria Lvova-Belova.
Instead of making plans to return the children, in a meeting broadcast on Russian state TV, Lvova-Belova asked Putin to make them Russian citizens.
In violation of international law, Russia has refused to provide Ukrainian authorities with a list of the children's names.
As the evidence continued to mount, the International Criminal Court issued arrest warrants for Putin and Lvova-Belova for war crimes against Ukrainian children.
It's a tense eight-hour drive to Ukraine's north-western border with Belarus.
Kateryna has been in constant contact with Bogdan but now her phone has gone quiet.
"I haven't heard anything, there is no connection right now, so I'm a bit worried," she says.
"I will only breathe a sigh of relief when they cross the border, when they text me that they have passed the Belarusian side."
This journey is even more dangerous because the group is travelling with an orphan boy.
"Russia believes that these are their orphans, that these are not Ukrainian orphans, but theirs, and they do everything to not let them through," she says.
After driving all day, we reach our rendezvous point, but the group have been held up at the Belarusian border crossing.
Hours go by before Kateryna gets word they've been let through.
With tears in her eyes, she watches the boys take their first steps back into Ukraine.
"Welcome to Ukraine! It's me who was texting you, calling and helping you!" she exclaims, as she runs to embrace them.
"You can breathe out now. All the scary things are behind you."
Watch Ukraine's Stolen Children tonight at 8pm on Foreign Correspondent, on ABC TV and ABC iview.