On 9 October 2006, North Korea conducted its first nuclear test explosion in North Hamgyong Province. The explosion was relatively low in yield – estimated at around 1 kiloton – and marked a dramatic breach of the international norm against nuclear testing established by the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

Despite the fact that the CTBTO's International Monitoring System (IMS) was only 60% operational at the time, the test was quickly detected by more than 20 seismic stations around the world.

Since 2006, North Korea has conducted five further tests. In 2009, 2013, two in 2016 and one in 2017, the latter – in September 2017 – being the most powerful and described as a hydrogen bomb.

Overview of nuclear test explosions

These test explosions have contributed to shape today's security policy landscape and demonstrate how crucial international monitoring and non-proliferation efforts continue to be.