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.

I've been hanging around the United Nations these past few days attending events related to consultations on lethal autonomous weapons systems—so-called killer robots. These are AI-powered weapons systems that can select and strike targets without human control. This is not the stuff of science fiction. These weapons exist today, and they are becoming more powerful—and, frankly, more accessible. They can be relatively inexpensive and deployed by both states and non-state actors, including terrorist groups.

As of now, there are no meaningful international regulations governing the use or development of these lethal autonomous weapons systems. There is a clear gap in our global governance of these technologies.

Here at the United Nations, delegates have been discussing ways to close that gap—potentially through a new legally binding international treaty to regulate or even ban some of these systems.

My guest today, Anna Hehir, is at the forefront of this effort. She is the Head of Military AI at the Future of Life Institute. In our conversation, Anna explains exactly what these weapons entail, where and how they are being used today, and what the future may look like if they continue to be developed without rules or oversight. We then discuss the process of getting a potential treaty on lethal autonomous weapons systems—and why, even if key players do not join such a treaty, it could still make a meaningful difference.

Eliana Johns hunts for nuclear weapons. She’s a senior research associate at the Federation of American Scientists, where her team uses open-source intelligence — or OSINT — to uncover secrets about countries’ nuclear capabilities and intentions. In fact, much of what we know today about China’s nuclear arsenal comes from her colleagues’ work, which used commercial satellite imagery to reveal that China is undertaking a massive nuclear buildup — at a pace far exceeding publicly available estimates from U.S. intelligence agencies.

In our conversation, Johns explains where OSINT has worked best and why greater transparency around nuclear weapons is essential for a more stable and peaceful world.

We recorded this live at the Carnegie International Nuclear Policy Conference.