Mysterious annex at North Korean missile plant has analysts puzzled

THE HAGUE, Netherlands — Construction at a North Korean missile factory could portend an upgrade to the country’s rocketry capabilities, according to satellite imagery and expert analysis.

The building activities, which began last year at the Chamjin missile factory, 20 driving minutes southwest of Pyongyang, involve a mysterious annex to a factory building that has left outside observers puzzled.

Named the Thaesong machine plant by North Korean state media, the Chamjin missile factory dates back to at least the 1960s, declassified U.S. Keyhole satellite imagery shows. The complex is nestled in a hard-to-access valley between three mountain peaks, secured by checkpoints on the entry roads, and defended by anti-aircraft nests. Wedged in the valley are two factory sites, some residential areas, a rocket engine test stand, and countless tunnel entrances into the sides of the abutting mountains.

At least two generations of the ruling Kim dynasty have visited the missile factory, images released by North Korean state media and independently geolocated reveal, which underscores its importance to the leadership.

Satellite images show that the western industrial area where the construction is currently underway has remained largely untouched for decades. Some of the factory halls were clearly dilapidated, with gaping holes in their roofs. In November 2023, the largest factory hall – the one now hosting the mysterious annex – received a makeover, including a new roof.

Then, in July 2024, large-scale construction began across the facility. Three industrial halls and a series of smaller buildings closer to the tunnel entrances were razed to the ground, foundations were laid for new, larger factory halls, and significant earth-moving work got underway. Simultaneously, the previously reroofed factory hall received its annex.

A known missile production site

A separate area of the same complex down the road to the east is known to be involved in the production of liquid-fueled missiles, with state media publishing images of leader Kim Jong-Un inspecting rockets and key components for the engines that appear to have been manufactured there.

A Burmese delegation visited the Chamjin complex in 2008 and reported that it was producing SCUD ground-to-ground missiles. A photo of such a missile that the delegation took appears to have been taken in the eastern section of the facility. Memoirs of an Iranian missile commander similarly include reference to a missile factory “on the road to Nampo,” the port city located to the southwest of Pyongyang.

An annotated satellite image from June 9, 2025, showing the ongoing construction in the western part of the Taesong Machine Plant, a known North Korean missile factory. (Planet Labs, provided by Middlebury Institute of International Studies. Annotated by Linus Höller.)

Less is known about the western area, where the new construction is taking place. In declassified CIA documents from the 1970s, the facility is described as being involved in the production of liquid-fueled anti-aircraft missiles. Parts of the factory are built into the side of a mountain, with several tunnel entrances visible.

Photos released by state media and located by analysts show Kim Jong-Il, the previous leader and Kim Jong-Un’s father, walking through tunnels at the facility. Thanks to these photos – some of which were seen hanging on the wall in a factory museum at the newer, eastern facility – we know that the two areas are organizationally connected.

Between the two halves, this western area is the only that has access to underground facilities, which are usually a staple of North Korean military sites for the relative safety they provide from air strikes. North Korea was all but flattened during the Korean War, when U.S.-led forces dropped 635,000 tons of bombs on the country.

Colin Zwirko, a correspondent for NK News, was the first analyst to publicly confirm the connection between the eastern and western complexes.

After the initial spurt in activity at the western site in 2024, a lull in construction followed. In North Korea, where labor laws are practically nonexistent and the army is commonly marshalled for building, some projects can be completed at breathtaking speed – but the country also faces severe resource constraints and quickly changing leadership priorities, so a halt to construction isn’t uncommon either, said Zwirko.

“That’s something Kim Jong-Un does all the time, where suddenly it will change and they build something new, you know, halfway through the project,” he said. Indeed, some time after the work on the large factory hall near the tunnel entrances stalled, the three large buildings down the road were demolished, and earth-moving work began there.

Observers said it’s too early to say for sure what role the new plant will play in the ecosystem of North Korea’s weapons technology. Confirmation may come only once Kim Jong-Un visits the completed facility and North Korean state media releases images of it. But based on the factory’s history, coinciding announcements and previous trends, some explanations seem particularly likely.

The known use of the Chamjin complex for missile production, coupled with visible architectural indicators, suggests that the area will continue to be involved in missile-related production. One such sign is the tall, narrow, windowless annex attached to the upgraded factory hall farthest down the street from the underground manufacturing tunnels.

The shape of the building suggests it is designed for testing long, tall objects, said John Ford, research associate at the California-based James Martin Center for Nonproliferation Studies, who has been tracking the North Korean missile program.

This undated picture released from North Korea's official Korean Central News Agency (KCNA) on March 2, 2016, shows North Korean leader Kim Jong-Un visiting the Thaesong machine factory in Nampo city. (KNS/KCNA/AFP via Getty Images)

Missiles fit this description, and not much else does, he said. Similar architectural features – although none exactly like the one in Chamjin – are visible in satellite imagery of other North Korean factories known to be involved in the production of transport-erector launchers, trucks carrying missiles for mobile launch capabilities.

Ford used satellite imagery and shadows to calculate the dimensions of the annex, which he says is around 65 meters long, 18 meters wide and about 15 meters tall. “That isn’t tall enough for the vertical on their largest missiles,” he said, which leaves “much to ponder.”

One possible explanation is that the rebuilt factory will be involved in the production of North Korean air-defense systems of the Pongae 5 or the newer Pongae 6 variant. The latter was announced by Pyongyang earlier this year but has not yet been publicly shown, Ford said.

The dimensions check out, as does the timing and the facility’s history – after all, the CIA had identified it as making anti-aircraft missiles of the SA-2 variety half a century ago. The factory hall with the annex may be involved in the assembly of trucks carrying the anti-aircraft missiles. The tall annex could be used to test the extension of the launcher tubes into their vertical position. The chassis would likely be produced elsewhere, said Ford.

“I speculate it’s likely, but it’s too early to know for sure,” he said.

An alternative explanation might be that the tall portion of the building is used for testing of another sort related to missiles.

“The reason why you would build it tall like this is you want to test the whole missile at once,” said Ford. It would be assembled inside the hall, then hoisted into place by a crane. “Then you would do whatever testing it is to the entire body of the missile.”

A spy satellite nexus?

Zwirko, the NK News correspondent, pointed out that the construction also coincided with North Korea’s announcement of a new engine for its satellite launch rocket. Last year, Kim Jong-Un announced an ambitious goal of launching three reconnaissance satellites, which the country failed to achieve. Pyongyang has since held radio silence on the topic.

“This could all come together to show us that it’s all stalled because they’re still working on the production of these engines at this factory,” Zwirko said.

But, he cautioned, there was no indication that North Korea was really in need of a mass production facility specifically for space launch engines. And when it comes to missile development, rather than space launch capabilities, North Korea is moving away from liquid fuel, he said, noting that there hadn’t been a liquid-fueled missile test in several years. North Korea has publicly announced its goal of making its entire missile arsenal solid-fuel, which requires no fueling up in the field before launch.

A particular focus of recent military factory upgrades in North Korea has been exports to Russia. For his war against Ukraine, President Vladimir Putin has been importing large numbers of North Korean-made missiles, shells and equipment. Many of the factories producing these items have undergone significant and rapid upgrades since the start of the Moscow-Pyongyang cooperation.

“If the pace is moving along quickly, it’s probably related to where they’re getting the money, which is Russia,” said Zwirko. “Watching for how quickly it finishes could tell us a lot about their priorities.”

He added: “There’s a lot of strange stuff going on with the weapons factories in the last couple of years.”

Linus Höller is Defense News' Europe correspondent and OSINT investigator. He reports on the arms deals, sanctions, and geopolitics shaping Europe and the world. He holds master’s degrees in WMD nonproliferation, terrorism studies, and international relations, and works in four languages: English, German, Russian, and Spanish.

荷兰海牙——根据卫星图像和专家分析，朝鲜导弹工厂的建设可能预示着该国火箭能力的升级。

去年在平壤西南方向 20 分钟车程的昌津导弹工厂开始的建筑活动，涉及一座工厂建筑的神秘附属建筑，这让外界观察人士感到困惑。

朝鲜官方媒体称之为“太城机械厂”的占津导弹工厂，根据美国解密的“钥匙孔”卫星图像显示，其历史至少可以追溯到上世纪60年代。该工厂群坐落在三座山峰之间一个难以进入的山谷中，入口道路设有检查站，并有防空炮阵地保护。山谷内分布着两处厂房、一些居民区、一个火箭发动机试验台，以及无数通往相邻山体的隧道入口。

朝鲜官方媒体发布的图片以及独立地理定位结果显示，至少两代金氏王朝统治者都曾参观过该导弹工厂，这凸显了该工厂对朝鲜领导层的重要性。

卫星图像显示，目前正在施工的西部工业区几十年来基本未受破坏。一些厂房明显破败不堪，屋顶上到处都是大洞。2023年11月，最大的厂房——也就是现在神秘附属建筑所在的厂房——进行了翻新，包括更换了屋顶。

随后，在2024年7月，整个厂区开始大规模建设。三个工业厂房和一系列靠近隧道入口的小型建筑被夷为平地，新的、更大的厂房开始打地基，大量的土方工程也随之展开。与此同时，之前翻新过屋顶的厂房也加盖了附属建筑。

一个已知的导弹生产基地

同一厂区东侧道路的另一区域据称参与生产液体燃料导弹，官方媒体发布了领导人金正恩视察火箭和发动机关键部件的照片，这些部件似乎就是在那里制造的。

2008年，一个缅甸代表团访问了昌津导弹基地，并报告称该基地正在生产飞毛腿地对地导弹。代表团拍摄的一张此类导弹的照片似乎是在该基地的东部区域拍摄的。一位伊朗导弹指挥官的回忆录中也提到了“通往南浦（位于平壤西南部的港口城市）的路上”有一家导弹工厂。

这张摄于2025年6月9日的卫星图像经过标注，显示了朝鲜导弹工厂——大城机械厂西部正在进行的建设。（图片由Planet Labs提供，米德尔伯里国际研究学院授权使用。标注者：Linus Höller。）

人们对正在进行新建设的西部地区知之甚少。在20世纪70年代解密的中央情报局文件中，该设施被描述为生产液体燃料防空导弹。工厂的部分建筑建在山体侧面，可以看到几个隧道入口。

朝鲜官方媒体发布的照片​​以及分析人士找到的照片显示，前领导人、金正恩的父亲金正日曾穿过该设施的隧道。多亏了这些照片——其中一些照片曾悬挂在位于东部新建设施的工厂博物馆的墙上——我们才知道这两个区域在组织上是相连的。

在朝鲜半岛南北两部分之间，只有西部地区拥有地下设施，而地下设施通常是朝鲜军事设施的标配，因为它们能提供相对安全的防空环境。在朝鲜战争期间，以美国为首的联军向朝鲜投掷了63.5万吨炸弹，几乎将朝鲜夷为平地。

NK News 的记者 Colin Zwirko 是第一个公开证实东西方建筑群之间存在联系的分析人士。

2024年西部工地最初的建设热潮过后，随后施工陷入停滞。兹维尔科表示，在朝鲜，劳动法几乎形同虚设，军队经常被征召参与建设，一些项目可以以惊人的速度完工——但该国也面临着严重的资源限制和领导层快速变化的优先事项，因此停工也并不罕见。

“金正恩经常这么做，项目进行到一半，突然就变卦，开始建造新的设施，”他说。的确，在隧道入口附近的大型厂房工程停滞一段时间后，道路尽头的三栋大型建筑被拆除，并开始了土方工程。

观察人士表示，现在断言这座新工厂将在朝鲜武器技术体系中扮演何种角色还为时尚早。或许只有金正恩视察完工的工厂，并且朝鲜官方媒体发布相关图片后，才能最终确认。但根据该工厂的历史、同期发布的公告以及以往的趋势，一些解释似乎尤为合理。

查姆金工业区用于导弹生产的已知用途，以及显而易见的建筑特征，表明该地区将继续从事导弹相关生产活动。其中一个标志是，在距离地下制造隧道最远的街道尽头，与升级后的厂房相连的那座高而窄、没有窗户的附属建筑。

加州詹姆斯·马丁防扩散研究中心的研究员约翰·福特一直在追踪朝鲜的导弹计划，他表示，该建筑的形状表明它是为测试长而高的物体而设计的。

这张未注明日期的照片由朝鲜官方通讯社朝中社于2016年3月2日发布，照片显示朝鲜领导人金正恩视察位于南浦市的太城机械厂。（KNS/KCNA/AFP via Getty Images）

他说，导弹符合这种描述，其他东西则很少符合。卫星图像显示，其他一些朝鲜工厂也具有类似的建筑特征——尽管没有一家与昌津工厂的完全相同——这些工厂也生产运输起竖发射车，即用于移动发射导弹的卡车。

福特利用卫星图像和阴影计算出了附属建筑的尺寸，他说该建筑长约65米，宽约18米，高约15米。“这个高度不足以支撑他们最大导弹的垂直发射，”他说，这“引人深思”。

一种可能的解释是，重建后的工厂将参与生产朝鲜的“苍鹰5”或更新型的“苍鹰6”防空系统。福特表示，平壤方面今年早些时候宣布了后者，但尚未公开展示。

尺寸、时间以及工厂的历史都与描述相符——毕竟，中央情报局早在半个世纪前就认定该工厂生产SA-2型防空导弹。带有附属建筑的厂房可能用于组装运输防空导弹的卡车。高大的附属建筑可能用于测试发射管的垂直伸展情况。福特表示，底盘很可能在其他地方生产。

“我推测很有可能，但现在下结论还为时过早，”他说。

另一种解释可能是，该建筑物的高层部分用于与导弹相关的其他类型的测试。

福特说：“之所以要建这么高，是为了一次性测试整枚导弹。”导弹会在大厅内组装，然后用起重机吊装到位。“之后就可以对导弹的整个弹体进行各种测试了。”

间谍卫星网络？

NK News记者兹维尔科指出，此次建设恰逢朝鲜宣布为其卫星运载火箭研发新型发动机。去年，金正恩宣布了发射三颗侦察卫星的宏伟目标，但朝鲜未能实现。此后，平壤方面对此事一直保持沉默。

“这一切可能表明，项目已经停滞不前，因为他们仍在这家工厂生产这些发动机，”兹维尔科说。

但他提醒说，目前没有任何迹象表明朝鲜真的需要专门用于大规模生产航天发射发动机的设施。他还指出，就导弹发展而言，朝鲜正在逐步淘汰液体燃料，而非航天发射能力，并提到朝鲜已经好几年没有进行过液体燃料导弹试验了。朝鲜已公开宣布其目标是使其所有导弹都使用固体燃料，这样就无需在发射前进行现场加注燃料。

朝鲜近期军工厂升级改造的一个重点是向俄罗斯出口。为了应对乌克兰战争，俄罗斯总统弗拉基米尔·普京大量进口朝鲜制造的导弹、炮弹和装备。自莫斯科与平壤开始合作以来，许多生产这些产品的工厂都经历了显著而迅速的升级改造。

“如果进展迅速，很可能与他们的资金来源有关，也就是俄罗斯，”兹维尔科说。“观察项目何时完成，可以让我们更好地了解他们的优先事项。”

他补充说：“近几年来，武器工厂发生了很多奇怪的事情。”

林努斯·霍勒是《防务新闻》的欧洲记者和开源情报调查员。他报道影响欧洲乃至全球的军火交易、制裁和地缘政治。他拥有大规模杀伤性武器不扩散、恐怖主义研究和国际关系三个硕士学位，并精通英语、德语、俄语和西班牙语四种语言。