WASHINGTON • North Korea has successfully produced a miniaturised nuclear warhead that can fit inside its missiles, crossing a key threshold on the path to becoming a full-fledged nuclear power, US intelligence officials have concluded in a confidential assessment.
The new analysis completed last month by the Defence Intelligence Agency (DIA) comes on the heels of another intelligence assessment that sharply raises the official estimate for the total number of bombs in the communist country's atomic arsenal.
The US calculated last month that up to 60 nuclear weapons are now controlled by North Korean leader Kim Jong Un. Some independent experts believe the number of bombs is much smaller.
The findings are likely to deepen concerns about an evolving North Korean military threat that appears to be advancing far more rapidly than many experts had predicted.
US officials last month concluded that Pyongyang is also outpacing expectations in its effort to build an intercontinental ballistic missile (ICBM) capable of striking cities on the American mainland.
While more than a decade has passed since North Korea's first nuclear detonation, many analysts believed it would be years before the country's weapons scientists could design a compact warhead that could be delivered by missile to distant targets. But the new assessment, a summary document dated July 28, concludes that this critical milestone has already been reached.
"The IC (intelligence community) assesses North Korea has produced nuclear weapons for ballistic missile delivery, to include delivery by ICBM-class missiles," the assessment states, in an excerpt read to The Washington Post.
The assessment's broad conclusions were verified by two US officials familiar with the document. It is not yet known whether the reclusive regime has successfully tested the smaller design, although North Korean last year officially claimed to have done so.
The DIA and the Office of the Director of National Intelligence declined to comment.
An assessment this week by the Japanese Ministry of Defence also concludes there is evidence to suggest that North Korea has achieved miniaturisation.
Mr Kim is becoming increasingly confident in the reliability of his nuclear arsenal, analysts concluded, explaining perhaps the dictator's willingness to engage in defiant behaviour, including missile tests that have drawn criticism even from North Korea's closest ally, China.
"Some like to depict Kim as being crazy - a madman - and that makes the public believe that the guy is undeterrable. He's not crazy and he's not suicidal. And he's not even unpredictable," said Dr Siegfried Hecker, director emeritus of the Los Alamos National Laboratory and the last known US official to personally inspect North Korea's nuclear facilities.
"The real threat," Dr Hecker said, "is we're going to stumble into a nuclear war on the Korean peninsula."