In the second installment of The Nuclear Threshold mini-series, we turn from missile defense to the human side of nuclear risk — the people, protocols, and split-second judgments that determine whether nuclear weapons are ever used. While deterrence is often framed as a stable system, history tells a far messier story: false alarms, malfunctioning sensors, training tapes mistaken for real attacks, and leaders operating under extreme pressure.

Our guest, Dr. Steve Fetter — Dean of the Graduate School at the University of Maryland, former Assistant Director in the White House Office of Science and Technology Policy, and member of the Bulletin of the Atomic Scientists’ Science and Security Board — walks us through how nuclear launch authority actually works inside the U.S. system. We explore why the president has sole authority, why that concentration of power is riskier than most Americans realize, and how “launch-on-warning” creates a decision window measured in minutes.

Steve breaks down famous near-miss incidents, the vulnerabilities of command-and-control systems, and his proposal to require concurrence from other top officials before any nuclear order is carried out. The conversation is grounded, accessible, and quietly unsettling — a reminder that deterrence relies on human beings who can make mistakes.

This episode asks a deceptively simple question with civilization-level implications:

How safe is a system that depends on one person getting everything right?