By WILLIAM J. BROAD and DAVID E. SANGERAUG. 14, 2017
North Korea’s success in testing an intercontinental ballistic missile that appears able to reach the United States was made possible by black-market purchases of powerful rocket engines probably from a Ukrainian factory with historical ties to Russia’s missile program, according to an expert analysis being published Monday and classified assessments by American intelligence agencies.
The studies may solve the mystery of how North Korea began succeeding so suddenly after a string of fiery missile failures, some of which may have been caused by American sabotage of its supply chains and cyberattacks on its launches. After those failures, the North changed designs and suppliers in the past two years, according to a new study by Michael Elleman, a missile expert at the International Institute for Strategic Studies.
Such a degree of aid to North Korea from afar would be notable because President Trump has singled out only China as the North’s main source of economic and technological support. He has never blamed Ukraine or Russia, though his secretary of state, Rex W. Tillerson, made an oblique reference to both China and Russia as the nation’s “principal economic enablers” after the North’s most recent ICBM launch last month.
Analysts who studied photographs of the North’s leader, Kim Jong-un, inspecting the new rocket motors concluded that they derive from designs that once powered the Soviet Union’s missile fleet. The engines were so powerful that a single missile could hurl 10 thermonuclear warheads between continents.
But since Ukraine’s pro-Russian president, Viktor Yanukovych, was removed from power in 2014, the state-owned factory, known as Yuzhmash, has fallen on hard times. The Russians canceled upgrades of their nuclear fleet. The factory is underused, awash in unpaid bills and low morale. Experts believe it is the most likely source of the engines that in July powered the two ICBM tests, which were the first to suggest that North Korea has the range, if not necessarily the accuracy or warhead technology, to threaten American cities.
“It’s likely that these engines came from Ukraine — probably illicitly,” Mr. Elleman said in an interview. “The big question is how many they have and whether the Ukrainians are helping them now. I’m very worried.”
Bolstering his conclusion, he added, was a finding by United Nations investigators that North Korea tried six years ago to steal missile secrets from the Ukrainian complex. Two North Koreans were caught, and a U.N. report said the information they tried to steal was focused on advanced “missile systems, liquid-propellant engines, spacecraft and missile fuel supply systems.”
Investigators now believe that, amid the chaos of post-revolutionary Ukraine, Pyongyang tried again.
The White House had no comment when asked about the intelligence assessments.
Last month, Yuzhmash denied reports that the factory complex was struggling for survival and selling its technologies abroad, in particular to China. Its website says the company does not, has not and will not participate in “the transfer of potentially dangerous technologies outside Ukraine.”
American investigators do not believe that denial, though they say there is no evidence that the government of President Petro O. Poroshenko, who recently visited the White House, had any knowledge or control over what was happening inside the complex.
How the Russian-designed engines, called the RD-250, got to North Korea is still a mystery.
Mr. Elleman was unable to rule out the possibility that a large Russian missile enterprise, Energomash, which has strong ties to the Ukrainian complex, had a role in the transfer of the RD-250 engine technology to North Korea. He said leftover RD-250 engines might also be stored in Russian warehouses.
But the fact that the powerful engines did get to North Korea, despite a raft of United Nations sanctions, suggests a broad intelligence failure involving the many nations that monitor Pyongyang.
Since President Barack Obama ordered a step-up in sabotage against the North’s missile systems in 2014, American officials have closely monitored their success. They appeared to have won a major victory last fall, when Mr. Kim ordered an end to flight tests of the Musudan, an intermediate-range missile that was a focus of the American sabotage effort.
Leon Panetta, the former C.I.A. director, said on CBS’ “Face the Nation” on Sunday that the North Korean drive to get workable ICBMs that could be integrated with nuclear weapons moved more quickly than the intelligence community had expected.
“The rapid nature of how they’ve been able to come to that capability is something, frankly, that has surprised both the United States and the world,” he said.
It is unclear who is responsible for selling the rockets and the design knowledge, and intelligence officials have differing theories about the details. But Mr. Elleman makes a strong circumstantial case that would implicate the deteriorating factory complex and its underemployed
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.
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.
The inferred size of the main engine matches that of a Ukrainian rocket engine suspected of being sold illegally to North Korea.
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.
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.
A version of this article appears in print on August 14, 2017, on Page A1 of the New York edition with the headline: Tracing Success Of North Korea To Ukraine Plant.