North Korean troops in Russia are not to be underestimated, former soldiers have told the BBC

What Haneul remembers most about his time in the North Korean army is the corrosive, constant hunger. He lost 10 kg in his first month of service, on a diet of cracked corn and moldy cabbage.

After three months of training, he says almost his entire battalion was severely malnourished and had to be sent to a recovery center to gain weight.

When they were later sent as frontline guards on the border with South Korea, rice replaced corn. But by the time I got to their bowls, many had been sucked out of their behinds and the rest had been sandblasted.

Haneul says his squad was among the best fed, a tactic to stop them escaping to South Korea. But he couldn't stop Haneul.

In 2012 he struck a deadly blow across the Demilitarized Zone (DMZ) – the strip of land separating the North from the South.

His experiences and those of other military defectors help shed light on the plight of the thousands of North Korean soldiers stationed on the front lines of Russia's war against Ukraine.

Pyongyang has he is reported to have sent about 11,000 troops to help Russian forces retake part of the Kursk region captured by Ukraine in a surprise summer offensive.

Earlier this week Seoul, said Washington and Kyiv soldiers had already entered the battle “in significant numbers” and reported the first casualties, with South Korean officials estimating that more than 100 had already been killed and more wounded. This figure has not been confirmed.

However, defectors and other military experts told the BBC that these troops should not be underestimated.

According to South Korean intelligence, most belong to the elite part of the Storm Corps and have “high morale” but “lack understanding of modern warfare”.

Only the taller, more athletic men are selected for the Storm Corps, says defector Lee Hyun Seung, who trained in North Korea's special forces in the early 2000s before defecting in 2014.

He taught them martial arts, how to throw knives and make weapons out of cutlery and other kitchen utensils.

But even though the training of the Storm Corps is more advanced than that of regular North Korean units, the soldiers are still not fed and even malnourished.

Online videos purporting to be of troops in Russia show younger, “frail” soldiers, Haneul says. They are a stark contrast to Pyongyang's propaganda videos, which show men breaking free from iron chains and smashing blocks of ice with their bare hands.

In his entire time in the military, Haneul says he only fired three rounds in one live-fire drill.

The closest I got to combat was when a hungry farmer stumbled into the DMZ looking for vegetables. Haneul says he ignored instructions to “shoot all intruders” and let the man go with a warning.

It's hard to know how much has changed in the decade since Haneul defected, given the paucity of information from North Korea. The country's leader, Kim Jong Un, appears to have channeled much of his limited resources into missiles and nuclear weapons rather than his standing army.

But according to another soldier, Ryu Seonghyun, who deserted in 2019, the first three years in the army were “incredibly difficult”, even for special forces. The 28-year-old, who served as a driver in the Air Force for seven years, says conditions deteriorated during his service and rice gradually disappeared from meals.

“Soldiers are sent into the mountains for days with little rice and are told it's part of their survival training.”

Given that these troops were trained to fight in the mountainous Korean Peninsula, the defectors doubted how well they would adapt to fighting on the plains and in the trenches of Kursk.

Most importantly, the Storm Corps is not a frontline unit. “Their mission is to infiltrate enemy lines and wreak havoc deep within enemy territory,” Ryu says.

But, he adds, Kim Jong Un has no alternative to send in special forces because regular soldiers spend most of their time farming, building or chopping wood.

“Kim Jong Un should have sent people who can demonstrate at least a certain level of combat capability to avoid damaging North Korea's reputation in Russia.

The language barrier seems to have created an additional obstacle. On Sunday, Ukraine's military intelligence department said communication problems led to North Korean soldiers accidentally firing on a Russian battalion, killing eight.

With these estimates, it's easy to dismiss the troops as “cannon fodder” and a sign of Russian President Vladimir Putin's desperation. But that would be a mistake, the defectors say. Their loyalty to the regime and fighting spirit will be of great importance.

“Most of the soldiers in the Storm Corps come from working-class families or farmers who are very obedient to the party and will follow orders without question,” said Hanul, whose father and cousin were in the special forces.

Intensive, ideological brainwashing sessions held every morning will further ensure they are mentally prepared, Lee adds. He believes North Korean troops “will get used to the battlefield, learn how to fight the enemy and find ways to survive.”

Although the soldiers wouldn't be given a choice about whether to deploy, Ryu thinks they'll be eager to go. The ambitious will see it as an opportunity to advance their careers, he says.

And given how difficult it is to serve in North Korea, some will relish the chance to experience life abroad for the first time.

“I think they will be more willing to fight than the Russian troops,” he adds, admitting that in their situation he would also like to be sent.

Chun In-bum, a former commander of South Korea's special forces, agrees with the defectors' assessments. “Just because they lack food and training doesn't mean they're incapable. They'll acclimate quickly. We shouldn't underestimate them.”

While 11,000 troops are unlikely to turn the tide of such a grueling war — Russia is estimated to be suffering more than a thousand casualties a day — experts and officials believe it could be just the first tranche, with Pyongyang potentially sending up to 60,000 or even 100,000 if they are replaced.

With these numbers, Mr. Chun believes they could prove effective.

In addition, Kim Jong Un will be able to absorb heavy casualties without affecting the stability of his regime, the former soldiers say.

“Those who have been sent will be people without influence or connections – to put it bluntly, those who can be sacrificed without problems,” says Haneul.

He recalls being shocked to learn that there were no children of high-ranking parents in his part of the front line: “That's when I realized we were indispensable.”

He does not expect much resistance from the families of the dead, whose sons he believes will be honored as heroes.

“There are countless parents who have lost a child after sending him to the army,” he adds, recalling his dead second cousin. His aunt received a certificate praising her son for his heroic contribution.

The loyalty of soldiers and their families may dampen Ukrainian and South Korean hopes that many will simply desert once they enter the fray. Kiev and Seoul have discussed conducting psychological operations on the front lines to encourage men to surrender.

But they don't seem to have access to cell phones. According to Ukrainian intelligence, even Russian soldiers' phones were seized before they clashed with North Korean troops.

So possible infiltration strategies include broadcasting messages over loudspeakers or using drones to drop leaflets.

Both Ryu and Haneul decide to defect after reading anti-regime propaganda sent across the border from South Korea. But they doubt it will work that far from home.

They say it takes a long time to build up the will and courage to defect.

Haneul also suspects that the police were ordered to shoot anyone who tried to escape. He remembers his comrades opening fire as he made his daring sprint across the DMZ.

“Twelve bullets flew just a meter above my head,” he says.

Even capturing North Korean troops could prove a challenge for Ukraine.

In the North, being a prisoner of war is considered extremely shameful and worse than death. Instead, soldiers are taught to take their own lives by shooting themselves or detonating a grenade.

Ryu remembers a famous war song titled Save the Last Bullet. “They tell you to keep two bullets, one to shoot the enemy and one to shoot yourself.”

However, former special forces coach Lee is determined to help. He offered to go to the front line to communicate directly with the soldiers.

“They are unlikely to escape in large numbers, but we have to try.” Hearing familiar voices like mine and others from North Korea can affect their psychology,” he says.

Haneul just hopes they go home to North Korea. He knows there is a chance some of his relatives are among the troops sent to help Russia.

“I just hope they make it and get back safely.

Additional reporting by Jake Kwon and Hosu Lee