Since September, North Korea has sent around 5,000 construction troops and 1,000 engineers to Russia. They are most likely engaged in infrastructure restoration and demining. In total, the number of North Korean personnel in Russia now exceeds 10,000.
https://united24media.com/latest-news/north-korea-sends-thousands-of-troops-to-russia-disguised-as-construction-workers-13103
https://x.com/wartranslated/status/1986084812919291973