Dnipro has been called the world’s fastest-shrinking city. The sprawling factory, southeast of Kiev and once a dynamo of the Cold War, is having a hard time finding customers.
American intelligence officials note that North Korea has exploited the black market in missile technology for decades, and built an infrastructure of universities, design centers and factories of its own.
It has also recruited help: In 1992, officials at a Moscow airport stopped a team of missile experts from traveling to Pyongyang.
That was only a temporary setback for North Korea. It obtained the design for the R-27, a compact missile made for Soviet submarines, created by the Makeyev Design Bureau, an industrial complex in the Ural Mountains that employed the rogue experts apprehended at the Moscow airport.
But the R-27 was complicated, and the design was difficult for the North to copy and fly successfully.
Eventually, the North turned to an alternative font of engine secrets — the Yuzhmash plant in Ukraine, as well as its design bureau, Yuzhnoye. The team’s engines were potentially easier to copy because they were designed not for cramped submarines but roomier land-based missiles. That simplified the engineering.
Economically, the plant and design bureau faced new headwinds after Russia in early 2014 invaded and annexed Crimea, a part of Ukraine. Relations between the two nations turned icy, and Moscow withdrew plans to have Yuzhmash make new versions of the SS-18 missile.
In July 2014, a report for the Carnegie Endowment for International Peace warned that such economic upset could put Ukrainian missile and atomic experts “out of work and could expose their crucial know-how to rogue regimes and proliferators.”
The first clues that a Ukrainian engine had fallen into North Korean hands came in September when Mr. Kim supervised a ground test of a new rocket engine that analysts called the biggest and most powerful to date.
Norbert Brügge, a German analyst, reported that photos of the engine firing revealed strong similarities between it and the RD-250, a Yuzhmash model.
Alarms rang louder after a second ground firing of the North’s new engine, in March, and its powering of the flight in May of a new intermediate-range missile, the Hwasong-12. It broke the North’s record for missile distance. Its high trajectory, if leveled out, translated into about 2,800 miles, or far enough to fly beyond the American military base at Guam.
On June 1, Mr. Elleman struck an apprehensive note. He argued that the potent engine clearly hailed from “a different manufacturer than all the other engines that we’ve seen.”
Mr. Elleman said the North’s diversification into a new line of missile engines was important because it undermined the West’s assumptions about the nation’s missile prowess: “We could be in for surprises.”
That is exactly what happened. The first of the North’s two tests in July of a new missile, the Hwasong-14, went a distance sufficient to threaten Alaska, surprising the intelligence community. The second went far enough to reach the West Coast, and perhaps Denver or Chicago.
Last week, the Bulletin of the Atomic Scientists featured a detailed analysis of the new engine, also concluding that it was derived from the RD-250. The finding, the analysts said, “raises new and potentially ominous questions.”
The emerging clues suggest not only new threats from North Korea, analysts say, but new dangers of global missile proliferation because the Ukrainian factory remains financially beleaguered. It now makes trolley buses and tractors, while seeking new rocket contracts to help regain some of its past glory.