
The North has said the test has realised its goal of being able to fit a miniaturised warhead on a rocket, prompting urgent talks at the UN Security Council and calls for new sanctions.
"An additional test could be conducted in a tunnel that branches off from the second tunnel or in the third tunnel, where preparations have been completed," said ministry spokesman Moon Sang-Gyun.
He said the South's military is on full combat-readiness to respond to "further nuclear tests, ballistic missile launches or land provocation". READ MORE