"It shocked me," said Michael Elleman, one weapons expert who noticed jarring similarities between the engine tested by North Korea in March and one he frequently encountered in Russia at the end of the Cold War. "It seemed to come out of nowhere."
After intensive study, Elleman, a former consultant at the Pentagon, and other specialists would report that they had detected multiple design features in the new North Korean missile engine that echo those of a 1960s-era Soviet workhorse called the RD-250.
There is no record of Pyongyang's obtaining blueprints for the Russian missile engine, and experts disagree on whether it ever did so. But the discovery of similarities has focused new attention on a question that has dogged U.S. analysts for at least the past two years: How has North Korea managed to make surprisingly rapid gains in its missile program, despite economic sanctions and a near-universal ban on exports of military technology to the impoverished communist state?
Many weapons experts say North Korea's startling display of missile prowess is a reflection of the country's growing mastery of weapons technology, as well as its leader's fierce determination to take the country into the nuclear club. But others see continuing evidence of an outsize role by foreigners, including Russian scientists who provided designs and know-how years ago, and the Chinese vendors who supply the electronics needed for modern missile-guidance systems.
Whether outsiders played a decisive role in Tuesday's firing of an intercontinental ballistic missile is not publicly known. But the evidence from the televised engine test in March is tantalizing, and also disturbing, analysts say. While North Korea is known to have obtained other Soviet missile designs in the past, the new revelations suggest the possibility of a transfer of weapons secrets that has gone undetected until now.
"It would mean that North Korea had a wider procurement network in the former Soviet Union than we had thought," said Elleman, a missile expert at the International Institute for Strategic Studies who oversaw the dismantling of Soviet-era missiles in Russia and Ukraine two decades ago. "My first question would be, 'What else have they got?' "
A foundation of knowledge
It was, without a doubt, one of the strangest mass arrests in the history of Moscow's Sheremetyevo-2 Airport: On Oct. 15, 1992, police detained 60 Russian missile scientists, along with their families, as they prepared to board a plane for North Korea.
Under questioning, the scientists confessed that they had been hired as a group to help the North Koreans build a modern missile fleet. In those early days after the collapse of the Soviet Union, there was little work for Russia's elite weapons scientists and little pay to help them feed and clothe their families.
"We wanted to make money and come back," one of the scientists explained at the time to a Russian journalist.
Scores of other scientists did make the journey in the 1990s, taking with them decades of experience, as well as parts and blueprints. It was the beginning of a Russian-influenced renaissance in North Korea's missile arsenal, which until then consisted mostly of outdated, early-generation Scuds, some of them purchased on the black market. About the same time, North Korea also obtained sensitive nuclear technology from Pakistani scientist Abdul Qadeer Khan.
The Russian government has insisted it had nothing to do with the transfer of missile secrets to North Korea. But Soviet designs became the templates for a series of intermediate-range ballistic missiles built and tested by North Korea over the next two decades, with extra features and capabilities added by a new generation of engineers recruited from the country's best schools.
Still, the program struggled, with many missiles blowing up on the launchpad, said Gaurav Kampani, a University of Tulsa international security expert and fellow at the Washington-based Atlantic Council.
"North Korea's ballistic missiles, especially its long-range missile project, were often considered a joke because of an unusual number of test failures," Kampani said.
The jokes all but stopped after North Korea achieved a series of technical breakthroughs in surprisingly rapid succession. Just in the past four years, Pyongyang has launched satellites into orbit and successfully tested one missile that can be fired from a submarine, as well as another that uses solid fuel, a significant military advance because it allows for more mobility and a much faster launch.
On Tuesday, its Hwasong-14 missile became the first in North Korean history capable of traveling more than 3,400 miles, the minimum distance needed to be classified as an intercontinental ballistic missile.
The missile is believed to be a two-stage version of the Hwasong-12, which carries the same engine North Korea put on public display in March.
In nearly every case, the technical foundations of the new missiles can be traced to know-how acquired from Russians and others over many years. Yet, the advances of the past years suggest that North Korea's engineers are now managing quite well on their own.
"The consensus has been that North Korea's program — missile as well as nuclear — is mostly indigenous," said Laura Holgate, a top adviser on nonproliferation to the Obama administration who stepped down in January as head of the U.S. mission to the United Nations in Vienna. "They continue to seek to import commercial dual-use technologies for their weapons programs, but the design and innovation is homegrown."
The many failures in the past were simply part of the learning curve for a country with a demonstrated ability to benefit from its mistakes, said David Albright, a former U.N. weapons inspector and president of the Institute for Science and International Security, a Washington think tank.
"Armed with the acquisition of many goods from abroad, North Korea appears to have devoted considerable resources to making the missiles domestically and, more importantly, figuring out how to launch them successfully," Albright said. "With regards to missiles, practice makes perfect."
Determined to succeed
Yet it is also clear that North Korea's engineers are continuing to benefit from designs bequeathed to them years ago. Before Pyongyang's new missile engine surfaced, U.S. officials fretted about the Hwasong-10, a mobile, intermediate-range ballistic missile that was successfully tested last June. The missile, which is capable of reaching targets as far as Guam, 2,000 miles away, has been shown in independent analyses to be a modified version of a Russian missile commonly known as the R-27 Zyb. North Korea is believed to have obtained the Russian blueprint in the 1990s and to have spent years working on prototypes, current and former U.S. officials said.
Elleman, the former Pentagon missile expert, believes that North Korea's newest missile engine has a similar past. The designs were most likely obtained years ago, through rogue scientists or on the black market, only to surface recently as part of a newly energized missile program.
Elleman is preparing to publish an analysis comparing the engine used in the Hwasong-12 and Hwasong-14 with the Soviet-era RD-250, using photos that highlight nearly identical features, including cooling tubes, exhaust nozzles and the four auxiliary engines that steer the rocket.
"They've had these designs for a long time, and they've probably been doing exercises around these engines for 15 years," he said. "All that work was done, and all [that] was left to do was the ground testing and flight testing with these different designs. It is what has allowed them to rapidly build up and try all these things over the past few years."
The Kim Jong Un factor
The key new element was most likely North Korean leader Kim Jong Un himself, who accelerated the pace of the country's nuclear and missile development soon after taking power. "They are serious about trying to create a capability that could threaten the United States," Elleman said.
The lingering Soviet legacy partly explains why North Korean technology tends to be decades behind that of the United States and other modern military powers, said David S. Cohen, a former deputy director of the CIA who had advised the Obama administration on North Korea's weapons advances.
"The missiles they're shooting now have some new engineering, but it's all based on old Soviet models," Cohen said.
Unable to purchase advanced technology on the open market, North Korea also remains dependent on smugglers and black-marketeers to obtain some of the parts it needs, particularly electronics, Cohen said.
But he cautioned against underestimating a North Korean leadership that repeatedly displayed ingenuity in working with old designs and systems as well as a determination to succeed in the face of international isolation and censure.
"It is a mistake to think that this is really a hermit kingdom that is cut off and doesn't have access to the Internet," Cohen said. "They have a lot of disadvantages, but the biggest part of the government economy is their nuclear and missiles program, so the smartest folks they have are directed to do this work.
"My fear," he added, " is that people underestimate them."