Condemning the test, South Korea said that it was a clear violation of the United Nations Security Council (UNSC) resolution.

But Pyongyang responded to the United States warning by saying the threat of "meaningless sanctions" was "laughable".

Mr Park cut short her visit to Laos and returned home, summoning a meeting of top officials to urgently review defences against what she termed "imminent" nuclear threats from the North.

But conservative lawmakers in South Korea have been raising concerns that such punitive measures have previously failed to deter Pyongyang from conducting a series of nuclear and ballistic missile tests in defiance of previous United Nations resolutions.

South Korea plans to mobilize its locally developed surface-to-surface ballistic missile arsenal for the operational concept, including Hyunmoo 2As, 2Bs and Hyunmoo 3s, according to the source.

"The cumulative knowledge of the five nuclear test explosions and the dozens of ballistic missile tests, especially in the last 12 months, are giving their technical people greater confidence that they can deploy warheads on their ballistic missiles".

On Friday, North Korea launched a nuclear test that sent seismic magnitude-5.0 shockwaves throughout the Korean peninsula.

This power strongly indicates a legitimate advance.

South Korea's president said the detonation, which Seoul estimated was the North's biggest in explosive yield, was an act of "fanatic recklessness" and a sign that leader Kim Jong Un "is spiralling out of control". "They aren't a backward state any more", Lewis said.

With the fifth and hitherto most powerful nuclear test by North Korea on Friday triggering global outrage, New Delhi is set to underline its concern over proliferation risk in India's neighbourhood, particularly over Pyongyang's secret ties with Islamabad.

In a statement on state-run television, North Korea said no radiation leaked in the blast. This means that Pyongyang likely can't develop different warheads for different missiles.

The government in Seoul will take "all diplomatic and military efforts to counter North Korea's continued provocation", senior presidential secretary for foreign affairs Kim Kyou-Hyun told reporters Sunday.

The North's announcement of its test indicated they had tested the bomb that would arm their missile units, said Jeffrey Lewis, director of the East Asia Nonproliferation Program at Middlebury Institute of International Studies at Monterey.

Tsuboi visited North Korea in 1999 to present a photo exhibition of the destruction caused by the 1945 atomic bombings of Hiroshima and Nagasaki and to interact with Korean hibakusha who lived in those cities at the time.