31.The comment comes as undisclosed Ukrainian and U.S. officials told The New York Times that North Korean troops had been taken off the front lines after suffering heavy casualties."These are standard measures – rotation due to large casualties," a military intelligence source commented for the Kyiv Independent, confirming the reports.Ukraine's Commander-in-Chief Oleksandr Syrskyi said on Jan. 19 that roughly half of the 11-12,000 strong North Korean contingent deployed to the embattled Russian region have been killed or wounded. Experts interviewed by the Kyiv Independent connected North Korea’s high casualty rates to a lack of experience with modern warfare, the "human wave" tactics employed against entrenched Ukrainian positions, and the resolve of North Korean troops to avoid capture, even at the cost of their own lives.Syrskyi nevertheless acknowledged that North Korean troops are trained and motivated soldiers who present significant challenges to Ukrainian soldiers.