North Korea is believed to have up to 60 nuclear warheads that can threaten regional stability, according to a recent estimate by a research institute affiliated with the US National Defense University.

The Institute for National Strategic Studies said in its Strategic Assessment 2020 report that the North is assumed to have between 15 and 60 nuclear warheads and approximately 650 ballistic missiles capable of threatening cities in South Korea, as well as in Japan and eastern China.

"Through the development of weapons of mass destruction, use of chemical weapons, and aggressive posturing of its conventional forces, the DPRK threatens regional stability and global norms," the report said, referring to the North by its official name.

"It has also tested intercontinental ballistic missiles that could be capable of striking the United States," it added.

The report pointed out that an overwhelming estimate of 1.2 million North Korean soldiers are "forward-deployed toward the Demilitarized Zone in an offensive posture" and continue to pose a conventional threat to South Korea and Japan.

Pyongyang has engaged in sales and transfer of military technology with Iran, helping to advance its ballistic missile programs, according to the report.

"Currency counterfeiting and narcotics trafficking have helped the regime generate funds and offset the effects of sanctions," it said.

An annual estimate of $1.25 million to $250 million of counterfeit US currency have been put into circulation by Pyongyang, the report said, adding that there is "a high degree of uncertainty regarding the value of this activity."

It said the North operates "more as a quasi-criminal enterprise than a legitimate nation-state." (Yonhap)