Reporting from Kyiv, ITV News Europe Editor James Mates hears from a friend of one of the two British men sentenced to death by pro-Moscow officials.
A friend of Aiden Aslin has told ITV News that it's "not even possible that he could be, or would be a mercenary", which is what the British fighter has been accused of and sentenced to the death penalty by a pro-Russian court in a separatist area of Ukraine.
Brennan Phillips said that Mr Aslin joined the Ukrainian marines in 2018 - long before Russia's invasion - meaning he should be treated as a prisoner of war and not subject to a trial.
"He has a home here in Ukraine," Mr Phillips said.
"His fiancée is Ukrainian. And he served as a uniformed service member in the Ukrainian marine core so it's not even possible that he could be, or would be a mercenary."
Mr Aslin is one of three men sentenced to death by pro-Moscow officials after being captured in Ukraine.Mr Aslin, 28, from Nottinghamshire and Shaun Pinner, 48, from Bedfordshire, were convicted of taking action towards violent seizure of power at a court in the self-proclaimed Donetsk People’s Republic (DPR).
The third man sentenced is reported to be Saaudun Brahim, a Moroccan national.
Previously speaking to ITV's Good Morning Britain, Mr Phillips described 28-year-old Mr Aslin as "a humble guy" adding that he wanted "to help people"."I trained Aslin in Syria. Aiden became a friend of mine, more so than a person that I trained. He's a humble guy, heart of gold," Mr Phillips said.
"He used to be a care worker, which is just a testament to who he is as a person. That's what compelled him to go to Syria to help people, and also why he came to Ukraine to help people here."
'He used to be a care worker, which is just a testament to who he is as a person,' a friend of Aiden Aslin says
Mr Phillips, a former US soldier, said it was wrong to described Mr Aslin as a "so-called mercenary" - a claim made by the Russians.
"Aiden is a Ukrainian. He signed up for the Ukrainian marine corp, he has a fiancee, a home here," he said.
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Meanwhile, Boris Johnson has instructed his ministers to "do everything in their power" to secure their release.
On Friday, Foreign Secretary Liz Truss also discussed efforts to secure the release of Aslin and Pinner with her Ukrainian counterpart, following the judgment by a Russian proxy court.
The trial has been widely seen as a sham.
Ukraine’s ambassador to the UK, Vadym Prystaiko, suggested negotiations for a possible prisoner swap with Moscow were underway, as it emerged Defence Secretary Ben Wallace made a surprise visit to Kyiv for talks with Ukrainian President Volodymyr Zelenskyy.
Mr Aslin, originally from Nottinghamshire, and Mr Pinner, from Bedfordshire, are both members of regular Ukrainian military units and had been fighting in Mariupol.
Aiden Aslin spoke to GMB six years ago explaining why he went to Syria to fight ISIS
As the diplomatic fallout intensifies, Downing Street have said the men are entitled to combatant immunity as prisoners of war under the Geneva convention.
A No 10 spokesperson said: “The prime minister was appalled at the sentencing of these men.
“He has been following the case closely and has asked ministers to do everything in their power to try and reunite them with their families as soon as we can.
“We completely condemn the sham sentencing of these men to death. There’s no justification at all for this breach of the protection they’re entitled to.”
Ms Truss said she discussed “efforts to secure the release of prisoners of war held by Russian proxies” during her call with Dmytro Kuleba, Ukraine’s minister of foreign affairs.
“The judgment against them is an egregious breach of the Geneva Convention,” she added.
Interfax, a Russian news agency, claimed the men would be able to appeal against their convictions.
Mr Phillips told GMB he did not think the death sentencing would be carried out.
"Emotionally, I worry about it, but logically I think about it and I do not think they'll be executed. I do think they'll be released, I have hope for that," he said.
"Anyone who's lived under Russian rule is not surprised about what's happened. Outraged, angered, but not surprised."