How did North Korea get missile engines?

Four months before its July 4 missile test, North Korea offered the world a rare technical preview of its latest missile engine, one said to be capable of lobbing nuclear warheads at U.S. cities. A video on state-run TV depicted a machine with thickets of tubes and vents, and a shape that struck some U.S. experts as familiar - in a distinctly Soviet way.

“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 nearuniversal 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 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.