My guest today, Zia Mian is co-director of Princeton University's Program on Science and Global Security. He's a physicist who has long studied nuclear weapons and nuclear security. In our conversation Zia Mian explains how scientists have impacted policy discussions about nuclear weapons since the dawn of the nuclear age, and how as the nuclear security landscape is evolving--and as science is advancing, scientists can continue to contribute to our understanding of the effects of a nuclear war.

In addition to his perch at Princeton, Zia Mian serves as Co-Chair of the Scientific Advisory Group of the United Nations Treaty on the Prohibition of Nuclear Weapons. This is the first first international scientific body created by a United Nations treaty process for the purpose of advancing nuclear disarmament and in our conversation he explains how the work of scientists can contribute to a nuclear free world.

We kick off, however, discussing the recent conflict between India and Pakistan and what this conflict says about the role of nuclear weapons in international security today.

We recorded this conversation in conjunction with the Carnegie International Nuclear Policy Conference. To view other episodes in this series please visit GlobalDispatches.org

On April 22, militants launched a brutal assault on a tourist site in Indian-controlled Kashmir, killing 26 civilians in what became the deadliest terrorist attack in India in nearly 15 years. What followed was the most intense military confrontation between India and Pakistan in decades—airstrikes, drone attacks, and a terrifying cycle of escalation that threatened to spiral out of control. Then, suddenly, came a ceasefire on May 10.

But why? And will it hold?

In today’s episode, I speak with Debak Das, Assistant Professor at the Josef Korbel School of International Studies at the University of Denver, to unpack the deeper roots of the Kashmir dispute and why it remains such a dangerous flashpoint between two nuclear-armed rivals. We explore how this crisis escalated so quickly—and why it stopped just short of the brink. Debak also offers sharp insight into the precariousness of the current ceasefire and what might come next.

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What would actually happen if a nuclear weapon were detonated in space?

This isn't just the stuff of science fiction — it's a scenario that researchers have studied closely, and the implications are deeply unsettling. From disrupting satellite a nuclear detonation in space would have immediate, global consequences — even without a single casualty on the ground.

In today’s episode, we’re exploring how our growing dependence on space-based infrastructure — for communications, surveillance, and national security — is changing the conventional calculus around nuclear deterrence.

How are major nuclear powers, including Russia, responding to this shifting landscape? Are we on the verge of a space-based nuclear arms race? And what can be done now to preserve space as a peaceful domain?

My guest is Bill Hennigan, author of the At the Brink series, which We recorded this conversation live at the Carnegie International Nuclear Policy Conference — and it’s a fascinating look into how the nuclear order may be evolving in ways that are still underappreciated.