North Korea is expanding a key weapons manufacturing complex that assembles a type of short-range missile used by Russia in Ukraine, researchers at a U.S.-based think tank have concluded based on satellite images.

The facility, known as the “February 11” plant, is part of the Ryongsong Machine Complex in Hamhung, North Korea's second-largest city, on the country's east coast.

Sam Lair, a research associate at the James Martin Center for Nonproliferation Studies (CNS), located at the Middlebury Institute of International Studies at Monterey, said the plant was the only one known to produce the Hwasong-11 class of solid-fuel ballistic missiles. Ukrainian officials say these munitions — known as the KN-23 in the West — have been used by Russian forces in their assault on Ukraine.