Six Ukrainian soldiers were killed several months ago in an attack on a vehicle donated by Welsh miners.
According to a Ukrainian trade union, the men were killed when their SUV was fired upon by Russian artillery in August.
The car was driven to Ukraine by Welsh miners as part of an aid convoy in February and some of the men killed were Ukrainian miners.
Only now have attacks on donated vehicles come to light, including one that was destroyed in 2022.
It is not known whether anyone was injured in the attack.
Carwyn Donovan, 36, from Abercraf, Powys, was driving the vehicle to Ukraine that was destroyed last month.
He looks at a photo of the wreck and points to the sticker he put on the front, which is now barely visible.
“You can still see the Ukrainian flag that we put on it before we left – it’s still there,” he said.
Mr Donovan has taken part in seven aid convoys to Ukraine.
He said it was “heartbreaking” to know that people had died when the vehicle was attacked.
“There is an overwhelming sense of sadness for the lives lost, but also deep admiration for their courage and selflessness,” he said.
“There is a sense of helplessness and even guilt, knowing that these people have paid the ultimate price for something that is in all our interests.”
The August attack took place in the Kharkov region, not far from the Russian border.
“This aid is of great importance,” said Olesia Briazgunova of the Confederation of Free Trade Unions of Ukraine.
She said the vehicles in particular were “an essential part of Ukraine’s defence”.
The vehicles are used by “defenders, volunteers, medics and rescue services – often saving lives, especially in regions close to hostilities,” she added.
Welsh miners delivered medicine, warm clothing and vehicles to Ukrainian miners in Kiev in February.
The link between Wales and Ukraine dates back to the 1980s, when Ukrainian miners, then part of the Soviet Union, donated part of their wages to striking miners.
The donated vehicles are used to deliver supplies to the front line and evacuate civilians from dangerous areas.
Currently, hundreds, if not thousands, of miners are fighting in the war against Russia.
Ukrainian soldiers sent a video message to miners in Wales thanking them for the vehicles and assistance.
They said: “Thanks to our British colleagues in the NUM (National Union of Mineworkers).
“Thank you to all the people of the UK for your continued support and help – the war continues,” they said.
Holding a Welsh flag in front of a donated vehicle, they said: “We fight every day for our independence and peace in Ukraine and across Europe.
“These vehicles help us save lives and bring us closer to victory.”
The NUM, a cross-party Senedd group and Welsh businesses have donated 25 vehicles since the conflict began in 2022, with funds being raised for a further five vehicles.
There are now plans for another aid convoy from Wales to Ukraine in October.
Former Welsh Government Counsel-General Mick Antoniw travelled with the convoy in February.
The MS Pontypridd has Ukrainian roots and members of his family died in the war.
He said the vehicles they provided are “vulnerable to artillery and drone attacks”.
“These vehicles we are delivering are saving Ukrainian lives on the front lines,” he said.
