The longest nuclear test-free period since 1945: what it means

As of 14 January 2026, the world has gone more than eight years since the last declared or detected nuclear weapon test explosion, the longest such period since testing began in 1945. 

Reached during the Comprehensive Nuclear-Test-Ban Treaty’s (CTBT) 30th anniversary year, this milestone reflects the value of transparency, the power of verification, and the spirit of multilateral cooperation.

Here is what sits behind the record, and why it matters.

The last confirmed nuclear test took place on 3 September 2017 at North Korea’s Punggye-ri site. Over 100 CTBTO facilities picked up the event within hours. Since then, no other nuclear test explosions have been declared or detected by this network.

This beats the previous record gap, from Pakistan’s last test in May 1998 to North Korea’s first in October 2006.

No ceremonies mark the moment. The achievement lives in what has not happened.

For decades after 1945, nuclear tests were frequent and widespread. More than 2,000 nuclear explosions were conducted worldwide, from Pacific atolls to remote deserts, often with lasting environmental and human consequences.

The CTBT’s opening for signature in 1996 marked a decisive shift. Fewer than a dozen nuclear weapon test explosions have been declared or detected in the years since. All six tests this century were picked up, and all were carried out by a single State.

Although the Treaty has not yet entered into force, it has helped establish a powerful global norm against nuclear weapons testing.

Confidence in this record rests on the CTBTO’s verification regime, anchored by the International Monitoring System (IMS), a network of more than 300 stations run by over 100 countries.

Using seismic, hydroacoustic, infrasound, and radionuclide technologies, it is designed to detect nuclear test explosions wherever they occur. 

Data from these facilities are transmitted to the International Data Centre (IDC) in Vienna, where analysts assess events and share findings with States Signatories.

This continuous flow of data, analysis, and reporting helps build confidence and reduce uncertainty.

The IMS is highly capable, but it was never intended to operate in isolation. The system was originally designed to detect nuclear tests with yields of around one kiloton of TNT equivalent (a tenth the size of the Hiroshima bomb). Continued technological advances have since pushed that capability to around half a kiloton.

As Executive Secretary Robert Floyd has noted, “below that level and using the same approach, reliable detection would require either a significantly expanded network or far more powerful data analysis tools.”

Floyd has also been clear about the limits of any technical system. “As any good scientist or diplomat would recognise, absence of evidence is not the same as evidence of absence,” he said. “Our system provides a high degree of confidence, but not an absolute guarantee and it was never intended to stand alone’.

Entry into force would unlock the full suite of verification tools, alongside the IMS, envisaged when the Treaty was negotiated were:

• Consultation and clarification: States could formally raise questions and seek answers from each other, clearing up ambiguity before it festers.
• Confidence-building measures: Voluntary transparency steps, backed by CTBTO expertise, to help show that nations are not testing.
• On-site inspections: If needed, teams could visit sites that had raised questions or concerns, allowing evidence to be gathered directly on the ground as a measure of last resort.

The CTBTO is already preparing for the future implementation of this capability, including through a major simulated on-site inspection exercise in Namibia in 2026.

This record-breaking period coincides with the CTBT’s 30th anniversary year, reflected in the theme One Treaty. One Goal. Zero Tests.

The milestone underscores what shared commitment and science can achieve, even in a challenging international climate. It also highlights what remains unfinished. Without entry into force, the test ban continues to rely on voluntary compliance rather than binding law.

As the world marks the longest silence since 1945, the question is no longer whether a nuclear test-free world is possible, but whether the international community is ready to take the final steps to secure that achievement for good.