There is evidence to suggest North Korea's burgeoning intercontinental ballistic missile program, supposedly hampered by sanctions and the lack of an open market for weapons, might be aided by Russia, if not smugglers on the black market, The Washington Post reported.

Michael Elleman, a weapons expert and former Pentagon consultant, has studied North Korea's now-rapidly advancing ICBM program, spotting eery similarities to the Soviet Union's RD-250s, according to the Post.

"It shocked me," Elleman told the paper. "It seemed to come out of nowhere.

"It would mean that North Korea had a wider procurement network in the former Soviet Union than we had thought. My first question would be, 'What else have they got?'"

Elleman, having studied Soviet rockets during the Cold War, pointed to similarities in the North Korean designs, "including cooling tubes, exhaust nozzles, and the four auxiliary engines that steer the rocket," according to the Post.

"They've had these designs for a long time, and they've probably been doing exercises around these engines for 15 years," Elleman added. "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 regime is "serious about trying to create a capability that could threaten the United States," Elleman told the Post.

"The missiles they're shooting now have some new engineering, but it's all based on old Soviet models," former CIA deputy director David S. Cohen, who advised the Obama administration on North Korea's weapons, told the paper.

Cohen fears Kim's regime has been underestimated for too long.

"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 told the Post. "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."