Gordon Chang, a North Korea expert who has written in recent days about Iran’s possible “secret program” there, described the State Department’s dismissal of these reports as naïve.

“Let me see if I get this straight: The country with the world’s most highly developed technical intelligence capabilities does not know what has been in open sources for years?” Chang said. “No wonder North Korea transfers nuclear weapons technology to Iran and others with impunity.”

“The North Koreans could go on CNN and say, ‘Hey, Secretary Kerry, we’re selling the bomb to Iran,’ and the State Department would still say they know nothing about it,” Chang said. “No wonder we’re in such trouble.”

Other Iranian experts specializing in the country’s military workings also have raised recent questions about Tehran’s collaboration with North Korea.