North Korea's Foreign Ministry condemned the three countries for pursuing an "outdated and absurd" plan, warning against taking actions that "incite hostility and collective conflict."

"As long as the hostile threat from the US and its allies exists, the DPRK's nuclear weapons will be a means of defending peace and sovereignty and a legitimate means of self-defense under the country's constitution," a North Korean foreign ministry spokesman said. North Korea also pledged to continue to strengthen its nuclear force.

On the South Korean side, the South Korean Foreign Ministry called on North Korea to stop its illegal weapons programs and return to the path of denuclearization.

"North Korea will never be recognized as a nuclear weapons state. We hope North Korea realizes that developing nuclear weapons and missiles only hinders its own security and economic development," said Lee Jae-woong, a spokesman for the South Korean Foreign Ministry.

The US-South Korea-Japan pledge came after talks on Saturday between US Secretary of State Marco Rubio, South Korean Foreign Minister Cho Tae-yul and Japanese Foreign Minister Iwaya Takeshi at a security conference in Munich, in which the officials reaffirmed their commitment to the complete denuclearization of North Korea.

The trilateral meeting between the United States, South Korea and Japan is the first since the inauguration of US President Donald Trump, who held historic summits with North Korean leader Kim Jong Un during his first term and praised their personal relationship.

Also on Tuesday, the South Korean military announced that it had deployed a new bunker-busting missile called the Korea Tactical Surface-to-Surface Missile (KTSSM), which was developed domestically.

The missile, nicknamed Ure, meaning "thunder" in Korean, is capable of carrying out rapid and precise strikes against North Korea's long-range artillery systems, which could threaten the Seoul area in the event of a contingency.

Ngoc Anh (according to KCNA, Yonhap, Reuters)