SEOUL: Nuclear-armed North Korea is advancing on the front lines of cyberwarfare, analysts say, stealing billions of dollars and presenting a clearer and more present danger than its banned weapons programmes.

Pyongyang is under multiple international sanctions over its atomic bomb and ballistic missile programmes, which have seen rapid progress under North Korean leader Kim Jong Un.

But while the world's diplomatic focus has been on its nuclear ambitions, the North has been quietly and steadily building up its cyber capabilities, and analysts say its army of thousands of well-trained hackers are proving to be just as dangerous.

"North Korea's nuclear and military programmes are long-term threats, but its cyber threats are immediate, realistic threats," said Oh Il-seok, a researcher at the Institute for National Security Strategy in Seoul.

Pyongyang's cyberwarfare abilities first came to global prominence in 2014 when it was accused of hacking into Sony Pictures Entertainment as revenge for "The Interview", a satirical film that mocked leader Kim.

The attack resulted in the posting of several unreleased movies online as well as a vast trove of confidential documents.

Since then the North has been blamed for a number of high-profile cyberattacks, including a $81 million heist from the Bangladesh Central Bank as well as the 2017 WannaCry global ransomware attack, which infected some 300,000 computers in 150 nations.

Pyongyang has denied any involvement, describing US allegations over WannaCry as "absurd" and a foreign ministry spokesman declaring: "We have nothing to do with cyberattacks."

But the US Justice Department in February indicted three North Koreans on charges of "participating in a wide-ranging criminal conspiracy to conduct a series of destructive cyberattacks".

In its 2021 Annual Threat Assessment Report, Washington acknowledged that Pyongyang "probably possesses the expertise to cause temporary, limited disruptions of some critical infrastructure networks" across the United States.

The North's cyber programme "poses a growing espionage, theft, and attack threat," said the document from the Office of the Director of National Intelligence.

It accused Pyongyang of stealing hundreds of millions of dollars from financial institutions and cryptocurrency exchanges, "probably to fund government priorities, such as its nuclear and missile programs".