Ukrainian Foreign Minister Dmytro Kuleba has said some 20,000 foreign fighters from 52 countries have signed up to take part in the battle.
There are no official figures available on the number of Australians fighting in Ukraine, but previous estimates put the number at between 200 and 600, despite warnings from the Australian government not to travel to the country.
Kjeldal had no military experience, only the will to go to the front to fight against Russia.
British welder James Durose first met Kjeldal on the Polish-Ukrainian border.
“How are you?” the Australian told Durose, 29, while being questioned by Ukrainian border guards.
Durose and Kjeldal then, along with an American, went to stay at one of the bases of the newly established Foreign Legion.
But given their lack of military experience, the three men were rejected.
At that point, Kjeldal told the two others to continue their studies and find another battalion to join.
“Me, Ninja and a guy from America left further east,” said Durose, who returned to Britain in September after suffering a head injury on the battlefield.
“In the beginning we had to search very hard to find a battalion. I think we were there about eight weeks without a battalion.’
The three men ended up in the northeastern city of Kharkov and came across an advertisement on Facebook by the Carpathian Sich Battalion, which welcomed foreign fighters.
They were hired and after a month of training in Kiev they were sent to the frontline in the northeast of the country.
The unit’s central task was to liberate the city of Izyum, which had been under Russian occupation since the early days of the invasion.
“We did a big attack that managed to get to Izyum, so we managed to take all of Izyum,” says Durose.
“That’s what we’ve been fighting for since we were on the front line, that was our goal. And that’s all me and Ninja said to each other, ‘Izyum is coming, we’re going to take Izyum’. And we have done that.”
But it was not without huge losses to their unit.
Kjeldal was seriously injured in mid-July after coming under heavy fire from a small group of Russian soldiers.
While the Australian was in hospital in Kiev, Durose was in a trench with another Australian, Doctor Jed Danahay, who was also from Queensland, when Russian soldiers ambushed them.
“He [Danahay] was killed right next to me,” says Durose.
“We were in a firefight, I was in a trench with Jed at the time. The Russian came at us from behind, he must have been about 10 meters away… I looked at Jed and said, “Is that one of our boys?” And he looked and said, ‘I don’t know, is it?’”
“I did what I had to do with that man, but we didn’t know there was another one” [Russian] man behind him … the man behind him shot Jed straight through the chest and got a British man straight through the head.”
“It was a pretty bad day, but we achieved great things with that attack, so we managed to get through to Izyum from that attack.”
A few weeks later, Durose was injured in a tank attack and returned to Britain to recover from his head injury. But his friend Kjeldal decided to return to the front.
“I beat the odds once, so let’s see if I can do it again I guess,” Kjeldal said in July.
Durose says his last conversation with his friend was shortly after his return to Britain.
“Glad you’re back,” Kjeldal said to Durose, letting him know that it had been relatively quiet on the front line after the unit captured Izyum.
But on Wednesday, Kjeldal and a man from Taiwan, Tseng Sheng-kuang, were on top of a hill when Russian tanks rushed toward them and fired. Both men were killed.
Kjeldal had developed a close relationship with Tseng as he spoke his language; the Australian had a Chinese wife and daughter who both still live in China.
The soldiers he served with say that Kjeldal constantly thought of his wife and daughter.
“He always sent them money, even though he was going through the hardest times,” says Durose.
“He had a heart of gold. He always had the best intentions. He was also a very comical guy, he was a funny guy.