In the years between 1945 and 1996 the nuclear-weapons states have carried out about one nuclear test per week. That adds up to over 2000 in total. But since September 1996, only three countries have undertaken nuclear tests. In this century, only North Korea has done so, with tests in 2006, 2009, 2013 and 2016 (twice).
What happened? – The Comprehensive Nuclear-Test-Ban Treaty (CTBT) was opened for signature. As well as discouraging testing, it also mandated the creation of the International Monitoring System (IMS) to provide a global monitoring capability to detect nuclear explosions. The IMS can detect vibrations in the earth, sound in water, or radionuclide particulates and noble gases released by nuclear explosions.
Original Article by Leigh Turner, Ambassador to Austria and UK Permanent Representative to the United Nations and other International Organisations in Vienna