More than 160 countries have ratified the Comprehensive Nuclear Test Ban Treaty (CTBT) since 1996. India and Pakistan have also conducted nuclear tests since then and are among eight countries including the United States and China preventing the treaty coming into force.
The head of an international body set up to monitor a planned ban on nuclear testing condemned North Korea's fourth nuclear test on Wednesday and called it a "wake-up call" for the international community.
North Korea said it had successfully conducted a test of a miniaturised hydrogen nuclear device, which would mark a significant advance in the isolated state's technological capability.
"This act constitutes a breach of the universally accepted norm against nuclear testing," Lassina Zerbo, head of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO).
"It is also a grave threat to international peace and security."
Wednesday's detonation was North Korea's fourth nuclear test, and second since young leader Kim Jong Un came into power in 2011. The isolated country last tested a nuclear device in 2013.
More than 160 countries have ratified the Comprehensive Nuclear Test Ban Treaty (CTBT) since 1996. India and Pakistan have also conducted nuclear tests since then and are among eight countries including the United States and China preventing the treaty coming into force.
Also read: North Korea says it has conducted successful hydrogen bomb test
"I sincerely hope that this will serve as the final wake-up call to the international community to outlaw all nuclear testing by bringing the CTBT into force," Zerbo said.
Meanwhile, The US vowed to respond appropriately to North Korea's provocations.
State Department Spokesman John Kirby said in a statement, "We will continue to protect and defend our allies in the region, including the Republic of Korea, and will respond appropriately to any and all North Korean provocations."
South Korea said it would take all possible measures, including possible United Nations sanctions, to ensure Pyongyang pays the price after its fourth nuclear test.
"Our government strongly condemns North Korea ignoring repeated warnings from us and the international community and pushing ahead with the fourth nuclear test, which clearly violated the U.N. resolutions," Cho Tae-yong, a senior security official at the South Korean presidential office said.
The UN Security Council is planning to hold an emergency meeting on Wednesday to discuss North Korea's reported test of a hydrogen bomb, the US mission to the United Nations said.
Speaking to Reuters on condition of anonymity, several diplomats said the meeting was scheduled to take place at 11 a.m. ET (1600 GMT). The diplomats said the meeting would likely be held behind closed doors.
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