13 February,2013 07:16 AM IST | | Agencies
The nuclear test was carried out in North Korea's Kilju county, North Hamkyung province. The world learnt of the nuclear test when an artificial earthquake with 4.9 magnitude was detected from the town where the North Korean nuclear test facility is located.
North Korea claimed the nuclear test was successful. South Korea's military was immediately put on heightened alert to deter potential cross-border provocations, while the South Korean and US forces upgraded their border surveillance level.
The South Korean defence ministry is keeping an eye on developments in North Korea to monitor potential signs of additional nuclear or missile tests.
Pyongyang vowed to proceed with missile and nuclear tests targeting the US, its âsworn enemy'. North Korea had conducted similar nuclear tests in 2006 and 2009. Japanese Prime Minister Shinzo Abe said the nuclear test conducted by North Korea was "regrettable". u00a0 u00a0 u00a0 u00a0