After months of rapt attention focusing on the thousands of North Koreans battling alongside Moscow’s troops close to Russia’s border with Ukraine, Pyongyang’s fighters appear to have vanished.

It has been roughly three weeks since Ukraine detected North Korean soldiers being involved in Russia’s attempts to push Kyiv’s forces from Kursk, said Colonel Oleksandr Kindratenko, a spokesperson for the Ukrainian Special Operations Forces.

Russia has been trying to end Ukrainian control of a chunk of territory in its Kursk region after Kyiv launched a surprise incursion in the late summer. Moscow has managed to peel back some of Ukraine’s grip, but Kyiv has retained its hold over a chunk of territory, including the town of Sudzha.

North Korea’s leader, Kim Jong Un — a staunch ally of Russian President Vladimir Putin—sent an estimated 12,000 North Korean soldiers to Russia that were quickly directed toward Kursk, intelligence reports suggested in the fall. Estimates from Ukraine have put roughly half this number as having been killed or injured, although this is not possible to independently verify.

Reports have been split on the effectiveness of the troops, which while hailing from a heavily militarized society, had no real combat experience. Some slapped the troops with the label of “cannon fodder,” while some Ukrainian sources have described the fighters as disciplined, in good shape, and adept with weapons.

It was North Korea’s supreme leader who proposed sending his country’s elite forces to Russia, The New York Times reported in recent days, citing U.S. intelligence.

Ukraine has typically described these highly-trained forces as being thrown into combat in waves of infantry assaults likely to yield high numbers of casualties.

Kindratenko told Newsweek they had little experience in the drone warfare so dominant in the nearly three years making up Europe’s largest land conflict since World War II, although they could move quickly and erratically to avoid being targeted by uncrewed aerial vehicles.

At least two of Pyongyang’s fighters are known to be in Kyiv’s hands. Ukrainian President Volodymyr Zelensky has published footage purportedly showing the interrogations of two different North Korean prisoners of war (POWs).

Kindratenko said that a Ukrainian special forces unit captured the first of two confirmed POWs in early January, tricking the fighter into surrendering rather than detonating a grenade.

South Korean and Ukrainian officials have said North Korean troops had been taking their own lives to avoid being captured by Kyiv. The U.S. said late last year it was aware of these reports, and that the soldiers likely motivated by a “fear of reprisal against their families in North Korea in the event that they’re captured.”

Zelensky said in mid-January that one POW had “expressed a desire to stay in Ukraine.” The other, the Ukrainian president said, wanted to return home.

Ukraine’s special forces gave the first captured North Korean POW medical attention, pulling him from the battlefield via a minefield, Kindratenko said. Russia launched artillery barrages and flooded the area with first person-view (FPV) drones as the soldier was extracted, the colonel said.

Russian forces “had a clear visual of our personnel evacuating the POW,” Kindratenko said.

“The intensity of the artillery barrage escalated at that moment, strongly indicating an attempt to eliminate both the POW and the extraction team, preventing the world from seeing a living DPRK soldier in Ukrainian custody.” DPRK, or Democratic People’s Republic of Korea, is North Korea’s official name.

Once the Ukrainian troops had brought the North Korean POW to a “secure location,” Kindratenko said, he was given a painkiller injection, plus food and water and cigarettes.

Before they disappeared—an absence attributed by Ukraine to crippling losses—the North Korean soldiers had been tasked with holding specific parts of Kursk, both in defensive and offensive operations. When they attacked Ukrainian positions, the colonel said, Pyongyang’s fighters sustained most of their casualties in the first few minutes of the assault.

They repeatedly attack along the “same routes where dozens of their troops have already been killed in action,” Kindratenko said.

Pyongyang’s troops were very mobile, with some of the fighters shedding the protective gear Russia had provided, he said.

“In some instances, they operate without helmets or ballistic plates to increase speed during assaults on Ukrainian positions,” Kindratenko said. Their confiscated backpacks held only scant food, a liter of water, and no cold-weather gear like gloves or thermal clothing.

Most of the space in the Russian-issued backpacks is taken up by ammunition, the colonel said. North Korean troops have more than three times the number of magazines than the average Russian soldier carries, Kindratenko said, plus the supplies of grenades and landmines.

Equipment recovered from the bodies of slain North Korean soldiers in Kursk indicate they are “often better armed” than Russian forces, the colonel added. Footage pulled from Ukraine’s extensive reconnaissance drones have shown a “significant number of anti-tank grenade launchers,” fired by Pyongyang’s forces against fortified, well-defended positions or vehicles.

“Nearly all” of the North Koreans carry “modernized variants” of standard-issue Russian weapons, the special forces colonel continued. Rather than the many-decades-old, if notorious, AK-47, North Koreans have been using much more up-to-date AK-12 assault rifles, he said.

Moscow and Pyongyang have swerved publicly acknowledging the deployment of fighters from North Korea, as well as the casualties racked up in fighting.

“Undoubtedly, there will be more POWs from North Korea,” Zelensky said in mid-January. What is not yet clear is when the North Korean soldiers will return to the battlefield, and whether more could be on their way to Russia.

It is possible that North Korean troops could head back to active combat after being bolstered by fresh training or as part of different types of attacks, Kindratenko said.