Pyongyang later claimed success in its sixth nuclear test.

Moon called for the most powerful punishment against the North in cooperation with the international community.

"The government decided to review all diplomatic solutions, such as a new UNSC resolution, to make North Korea give up its nuclear development program in a complete, verifiable and irreversible way and completely isolate North Korea," said Chung, also the head of the NSC standing committee.

He also said the country and its US ally will discuss the possible deployment of what he called the "most powerful US tactical assets" to South Korea.

The top security adviser did not elaborate, but the move comes amid a growing call here for the redeployemnt of US tactical nuclear weapons to South Korea.

The US, Seoul's ally, removed its nuclear weapons from South Korea in the early 1990s when Seoul and Pyongyang reached an agreement to keep the Korean Peninsula nuclear-free.

"The president ordered (the military) to prepare active measures to counter North Korea's reckless provocations based on the strong Korea-US alliance and to maintain complete readiness against additional provocations," Chung said.

Saying he held two telephone conversations with his US counterpart H.R. McMaster before and after Seoul's NSC meeting Sunday, Chung said the top security advisers of the two allies agreed to arrange a telephone conversation between their leaders in the near future to discuss the countries' joint efforts to rein in North Korea's evolving nuclear and missile technologies.

North Korea has staged nine missile launches since the new South Korean president took office in May. (Yonhap)