Chun In-bum, a former commander of South Korea's special forces, agrees with the defectors' appraisals. "Just because they lack food and training, does not mean they are incapable. They will acclimatise quickly. We should not underestimate them."

Bennett, a defense researcher and North Korea specialist at RAND, said that Kim Jong Un is taking risks by sending troops to support Russia, especially potential elite-class military personnel.He said that Kim is unlikely to want to return the bodies of those killed to their families,

Far from their homes in one of the world’s most isolated and secretive states, about 11,000 North Korean soldiers find themselves at the center of Europe’s biggest conflict since World War II.