Construction has resumed and expanded on a project to upgrade a key North Korean nuclear missile factory, according to NK Pro analysis of satellite imagery, as the munitions industry enters the final stretch of leader Kim Jong Un’s five-year weapons development plan.

The expansion project at the Thaesong Machine Factory near Pyongyang, believed to be involved in long-range missile engine production, started last July before progress halted between early December and mid-March.

Planet Labs satellite imagery now shows that work resumed in the second week of March on new buildings outside entrances to underground facilities at the site. Construction also started around the same time on a new cluster of buildings in a separate area nearby, expanding the scope of the project.

Then, between March 23 and 28, an existing production building in the main area of the factory was demolished, likely to make room for more modern facilities. This is next to another large production hall which was rebuilt around a year ago.

The exact purpose is not yet known and likely won’t become apparent unless state media reports on Kim visiting the site either during construction or after it is completed.

But an NK Pro analysis published last year detailed evidence that the factory’s western complex, where construction is now taking place, likely housed liquid-fuel engine production lines for long-range missiles or satellite carrier rockets in the past.

A separate Thaesong Machine Factory complex just up the road to the east has featured in state media numerous times during the Kim Jong Un era, hosting inspections of nuclear warheads and intercontinental ballistic missile (ICBM) assembly, while scenes of Kim Jong Il in the western complex tunnels still appear occasionally on state TV.

The current leader’s most recent confirmed appearance at Thaesong was in Jan. 2023, when state TV released a single photo of Kim and his young daughter in a room full of dozens of intermediate-range ballistic missiles (IRBMs). 

Existing evidence suggests the eastern complex has been used for final liquid-fuel IRBM and ICBM assembly and the western complex for rocket engine production, but additional functions are not confirmed.

The latest construction project may be related to North Korea’s stated aim of developing a new liquid-fuel engine for the country’s military reconnaissance satellite program.

Since Pyongyang has not offered public updates on the program since last summer, it’s possible the pause in construction was caused by additional reassessments of rocket engine production goals after the most recent launch last May ended in failure. 

It’s also possible that the project aims to convert Thaesong’s western complex facilities to produce something other than liquid-fuel engines, though it is likely to be weapons-related considering the factory’s history.

Meanwhile, North Korea also expanded a uranium enrichment facility known as Kangson near the Thaesong factory last year as part of Kim Jong Un’s demands to “exponentially” increase nuclear warhead production.

North Korea’s most recent ICBM test — its newest solid-fuel model named the Hwasong-19 — was last October. 

Pyongyang has focused on solid-fuel missile development while not testing any liquid-fuel missiles in over two years. Liquid-fuel missiles also weren’t featured at a major weapons expo last November, though some appeared in images of Kim visiting missile bases in October.

Edited by Alannah Hill