South Korea Warns North is Gearing for Nuclear Test

North Korea is preparing a nuclear test in the coming days, a South Korean government official has warned.

According to the anonymous official cited by CNN, the entrance to North Korea's Punggye-ri nuclear test site was sealed, a sign of completed preparation for a nuclear test.

"This is the final step in preparing to test a nuclear device. In theory, there are seven to 14 days to conduct a test once the entrance is sealed", the South Korean official said.

There is also a possibility that instead the North could attempt launching a long-range ballistic missile.

In an interview for South Korean newspaper Joonang Ilbo ahead of his visit to Seoul, US President Barack Obama cautioned the North to expect "a firm response from the international community" if it engages in a nuclear test.

On its part, North Korea views Obama's visit to East Asia as "an escalation of confrontation in the region".

In March, Pyongyang fired 30 short-range missiles in response to the preparation of US-South Korean joint military drills.

The two Koreas are still technically in a state of war, ever since the end of the Korean War in 1953.