North Korean ballistic missiles fired at Ukraine by Russian forces since late December have been far more precise than salvos of the weapons launched over the past year, two senior Ukrainian sources told Reuters.

When Ukrainian soldiers captured two North Korean prisoners of war last month, it provided the first undeniable proof of Pyongyang’s direct involvement in the war against Ukraine.

North Korean troops have been pulled back from the frontline amid devastating losses, according to Ukrainian and American officials. Kim Jong Un ’s forces have not been seen on the battlefield for around three weeks, Ukrainian special forces said, according to the New York Times.