North Korea unveils new nuclear warheads

North Korea unveiled new, smaller nuclear warheads and vowed to produce more weapons-grade nuclear material to expand the country's arsenal, state media KCNA said yesterday, as a US aircraft carrier arrived in South Korea for military drills.

KCNA released photos of the warheads, dubbed Hwasan-31s, as leader Kim Jong Un visited the Nuclear Weapons Institute, where he inspected new tactical nuclear weapons and technology for mounting warheads on ballistic missiles, as well as nuclear counterattack operation plans.

Experts say the images could indicate progress in miniaturising warheads that are powerful yet small enough to mount on intercontinental ballistic missiles capable of striking the US.

"It has something more powerful in a smaller space. That's worrisome," said Kune Y. Suh, professor emeritus of nuclear engineering at Seoul National University, comparing the new warheads to the 2016 version.

Kim Dong-yup, a former South Korean naval officer who teaches at Kyungnam University, said the warheads were most likely designed for use with at least eight different delivery platforms listed in posters on the wall.

"Those are not limited to tactical missiles but appear to be a miniaturised, lightweight and standardised warhead that can mount on various vehicles," he said.

"Now that the delivery vehicles are nearly ready, they would churn out warheads to secure second strike capabilities - perhaps hundreds, not dozens - while running centrifuges even harder to get weapons-grade nuclear material," he added

Kim Jong Un ordered the production of weapons-grade materials in a "far-sighted way" to boost its nuclear arsenal "exponentially" and produce powerful weapons, KCNA said. 

He said the enemy of the country's nuclear forces is not a specific state but "war and nuclear disaster themselves," and the policy of expanding arsenal is solely aimed at defending the country.