Report: North Korean nuclear arsenal expanding

The figures, which were published in the "Wall Street Journal" on Thursday, were presented to US nuclear specialists in a closed-door meeting in February.

The estimate is significantly higher than any previously known Chinese assessment. It also exceed those recently made by US experts who put North Korea's current arsenal at between 10 and 16 nuclear weapons - suggesting that Pyongyang is moving faster down the nuclear path than previously thought.

Challenges to denuclearize

Experts now believe that North Korea's sizeable nuclear stockpile could further complicate international efforts to persuade Pyongyang to denuclearize.

"The more they believe they have a fully functional nuclear arsenal and deterrent, the more difficult it's going to be to walk them back from that," Siegfried Hecker, a leading expert on North Korea's nuclear program told the "Wall Street Journal."

Beijing concerns

In Beijing, there is growing concern about the nuclear ambitions of its wayward ally, which carried out nuclear tests in 2006, 2009 and 2013.

A recent US report warned that North Korea appeared poised to expand its nuclear program over the next five years, claiming that, in a worst case scenario, it could have up to 100 atomic arms by 2020.

In 2012, Pyongyang demonstrated its rocket capabilities by sending a satellite into orbit. A test to show it has mastered the re-entry technology required for an inter-continental ballistic missile (ICBM) has yet to be conducted, however.

Ongoing progress

Expert opinion on how much progress North Korea has made remains divided. One key question is how close the North is to being able to miniaturize a nuclear device which could be fitted on the tip of a missile.

In a white paper published in January, the South Korean defense ministry said North Korea had already developed its miniaturization technology to a "significant" level.

ksb/kms (AFP, dpa)