Ukraine, the United States and South Korea have accused North Korea of providing Russia with more than 10,000 soldiers to fight against Ukraine.
The troops are now fighting in the Kursk region, wearing Russian uniforms and using Russian weapons, according to Germany's dpa news agency.
Ukraine announced it had captured two North Korean soldiers over the weekend.
Ukrainian President Volodymyr Zelenskyy expects there will be more prisoners from North Korea.
"It's only a matter of time before our troops manage to capture others," he wrote on X. "There should be no doubt left in the world that the Russian army is dependent on military assistance from North Korea."
Kyiv is ready to hand over the prisoners to North Korean leader Kim Jong Un if he organizes the release of Ukrainian prisoners of war held by his close ally, Russia.
POWs have some options
However, the captured soldiers have other options if they do not want to return to their authoritarian homeland.
"These two men, and any other North Koreans who are captured, have three options," said Chun In-bum, a retired lieutenant general in the Republic of Korea Army and now a senior fellow with the National Institute for Deterrence Studies.
"They can request to be returned to North Korea, they can stay in Ukraine or they can ask to go to a third country," he said.
"It only makes sense if that third country is South Korea and I would say that they would be welcomed."
Zelenskyy: N Koreans should not die in battles in Europe
Zelenskyy released video footage purporting to show the injured combatants being interrogated.
One of the soldiers can be heard speaking to a Ukrainian official through an interpreter, saying that he did not know he was going to fight in a war with Ukraine and that his commanders "told him it was just training," reported France's AFP news agency.
In translated comments cited by AFP, one of the men says he wanted to return to North Korea. The other said he will do what he is told but, if given the chance, wanted to live in Ukraine.
Discussions are currently underway with South Korean diplomats to outline the potential consequences of their return to North Korea.
"They would be immediately executed," Chun told DW.
"For the North Korean regime, the main consideration is secrecy. The fact that these men surrendered instead of taking their own lives, as documents that have been captured by the Ukrainians show they were ordered to do, means they failed to follow order," he said.
"The most important thing for the North Korean regime is to maintain their control and they do not want wounded soldiers returning home to tell their families and friends what went on in Russia," he added.
Neither North Korea nor Russia have confirmed that Pyongyang's troops are fighting against Ukraine, with the North's complete control over domestic media meaning that the vast majority of its citizens are also unaware.
North Korea's mounting death toll
South Korea's intelligence service, working with the Ukrainian government, estimates that at least 300 North Korean troops committed to the conflict have been killed and a further 2,700 wounded.
Toshimitsu Shigemura, a professor who specializes in North Korea's leadership at Tokyo's Waseda University, is equally convinced that the regime in Pyongyang would not permit the men to return to their previous lives and, potentially, recount what they had experienced.
"I think it is almost certain that they would be killed, although it is possible that they would be sent to prison, which is effectively a death sentence anyway," he told DW, adding that it was unfortunate that the men's faces have been shown on social media.
North Korean troops suffer 'mass casualties' in Russia
"If they choose not to return, then their families will be sent to prison camps where they will die, so these men may think that they could avoid that if they do agree to go back," Shigemura said.
"Whether they choose to return or not, the authorities in North Korea will not want news of what has happened in Russia to be passed on to the rest of the population."
Shigemura believes that Kim Jong Un's decision to commit troops to Vladimir Putin's war was a mistake because it will be virtually impossible to quell rumors when the soldiers return home or their family members are told they are dead.
"It is a huge headache for the government there because the last thing they want is for the troops to come back and talk about it," he said.
"North Koreans have not been told that their sons are fighting for Russia against Ukraine and they will of course want to know why."
"The rumors will only spread and I think this was a bad error by Kim," Shigemura said, adding that it is possible that Kim over-estimated the abilities of his forces or under-estimated the strength of Ukraine's resistance.
It is also possible, he said, that Putin misled his ally on the dangers involved in the operation.
Several media reports suggest that Russia is deploying lightly armed and poorly trained North Korean troops in "human wave" attacks against prepared Ukrainian positions and keeping Russian troops in reserve.
Chun believes the two prisoners — as well as others who might follow in the future — will "do the wise thing and go to South Korea."
"Whatever happens, this is a tragedy," he said. "These are two young guys who were told they were going on a training exercise and then they found themselves on the front lines and injured. Their government has lied to them. It is an evil regime. These men are just like us and I can only feel sorry for them.
Edited by: Keith Walker