Who knows how true this is, but apparently 7,000 North Koreans are now deployed near Ukraine’s border with Russia:

Kyiv’s defense intelligence agency has said Russia appears to have deployed more than 7,000 North Korean soldiers, armed with AK-12 rifles, mortar rounds and other assault weapons, to areas near the border with Ukraine.
South Korea and the West have warned that North Korean troops in Russia may soon enter into combat against Ukraine that would pose a major security threat to both Europe and the Indo-Pacific region.
The Defense Intelligence of Ukraine (DIU) said on Saturday (local time) that Russia moved more than 7,000 North Korean soldiers from Russia’s coastal region to areas near Ukraine last week.
“The North Korean troops were moved to the frontline with the help of at least 28 military transport aircraft of the Russian Aerospace Forces,” the DIU said on its website.
You can read more at the link.