In a given month, more than 100 million people open Pokémon Go—the app that allows users to superimpose the world’s most profitable media franchise onto reality using only their smartphone. Using their phone camera and a flick of the wrist, they captured tiny digital monsters at the park, at the office, sometimes in active minefields, and, yes, in the bathroom.

Who else was watching?

A seasoned scholar, strategist, and expert in space policy and strategy, Dr. John J. Klein is well-versed in applying strategic theory to the space domain. In his new book, Fight for the Final Frontier: Irregular Warfare in Space (2023), Klein argues that irregular warfare, in both its military and nonmilitary forms, is a vital and underutilized concept for understanding malicious activities in space and the nature of space warfare. His argument draws on a diverse list of strategic theorists, historians, and contemporary policy analyses. Klein weaves these sources together persuasively, providing an accessible overview of a technologically demanding subject. Policy generalists and students, along with veteran analysts of space policy, will benefit from his account.