When did North Korea conduct its first underground nuclear test?

North Korea conducted its first underground nuclear test on October 9, 2006. The explosion occurred at the Punggye-ri Nuclear Test Site, located in the northeastern Hamgyŏng Mountains.12

The test yielded less than two kilotons, which was significantly lower than the initial tests conducted by other nuclear-armed states. Although the test was only partially successful, it served as a demonstration that North Korea had become a nuclear-armed state, leading to widespread international concern and the imposition of increased sanctions.12