The Comprehensive Test Ban Treaty, better known as the CTBT, expressly prohibits its signatories from testing nuclear weapons. It was opened for signature in 1996 and is now one of the most widely adopted treaties in the world.

Since the Comprehensive Nuclear-Test-Ban Treaty was opened for signature in 1996, there have been ten nuclear tests conducted worldwide. These include two tests by India and two by Pakistan in 1998, and six tests by North Korea between 2006 and 2017 .​ This limited number of tests since 1996 stands in stark contrast to the more than 2,000 nuclear tests conducted in the preceding five decades, highlighting the CTBT's significant role in establishing a global norm against nuclear testing

My guest today, Robert Floyd, is the Executive Secretary of the Comprehensive Test-Ban Treaty Organization, which—as the name suggests—is the international body responsible for monitoring and facilitating the implementation of this treaty. It does so, in part, through a sophisticated global monitoring system capable of detecting a nuclear test anywhere in the world. I sat down with Robert Floyd on the sidelines of the Carnegie International Nuclear Policy Conference in Washington, DC, earlier this month, where he explained why the CTBT has been so successful in constraining nuclear testing—and what challenges the treaty now faces amid a rapidly shifting geopolitical landscape.

This episode is produced in partnership with Lex International Fund, a philanthropic fund dedicated to strengthening international law to solve global challenges. It is part of a series that demonstrates the impact of Treaties on state behavior that we are calling "when treaties work"