The United States continues to monitor North Korea's nuclear projects, including ballistic missile technology, the White House said today.

White House national security spokesman John Kirby said the US has made clear it is open to talks on denuclearization of the Korean Peninsula.

North Korean leader Kim Jong-un today showed for the first time photos of centrifuges that produce fuel for nuclear bombs.

As reported by the state news agency KCNA, during a visit to the Nuclear Weapons Institute and a production base for "nuclear weapon materials," Kim stressed "the need to further increase the number of centrifuges in order to exponentially increase nuclear weapons for self-defense in line with the party's nuclear armed forces building line'.

Kim also oversaw the test firing of a new 600mm multi-barrel rocket launcher.