North Korea's nuclear-armed submarine was announced Friday but its neighbor and experts seemed unimpressed with it.

An official of South Korea's Joint Chiefs of Staff told reporters in Seoul that the sub is not capable of normal operation based on its external features, Yonhap reported.

The JCS official based the assessment on the parts of the submarine that have been enlarged to carry a missile.

Joseph Dempsey, a researcher at the International Institute for Strategic Studies, wrote on X that the sub's core "is an obsolete Romeo class diesel-electric boat, originally designed in the 1950s."

Dempsey added, "As a platform it will have some fundamental limitations and vulnerabilities."

Nevertheless, United States-based analyst Ankit Panda said the sub named Hero Kim Kun Ok "will increase the complexity of the nuclear threat posed by North Korea."

North Korean leader Kim Jong Un presided over the unveiling ceremony on Wednesday, state news agency KCNA reported.

"The fact that the nuclear attack submarine, considered a symbol of invasion against our republic for decades, now symbolizes our power that terrifies the shameless enemies and that it is a new attack submarine of our own style unseen by the world, is truly something welcomed by all our people," Kim said during his speech, hinting that the latest move was aimed at countering US nuclear-powered submarines, according to Yonhap.

North Korea will turn its existing submarines into attack vessels equipped with nuclear weapons, Kim said.

According to the Nuclear Threat Initiative, a US-based think tank, North Korea is estimated to have between 64 and 86 submarines, one of the world's largest fleets.

However, experts doubt if all of them are operational given their age, according to NTI.

WITH AFP