“Fight for the Final Frontier should be required reading across the professional military education community. The application of irregular warfare theory is a fresh perspective to view the current and evolving conflict in space.”—Mike Fowler, Associate Professor of Military and Strategic Studies, editor of Military Strategy, Joint Operations, and Airpower

"Klein consults and teaches space policy and strategy. War in space is unique because of the characteristics of the domain. Still, since conflict is a duel between humans, there are strategic insights—from Sun Tzu to Clausewitz to Mahan—that can be applied (with caution) to the space domain. Conflict in space is likely to be long, indecisive, messy, and very political. Klein's praiseworthy effort to apply irregular war theory to space is especially useful and valuable. Concepts like hybrid warfare, protracted operations, lawfare, attrition, terrorism, friction, deception, cumulative strategies, non-state actors, dispersal, coordination, maneuver, and surprise are critically important. If the book has any shortcomings, it is downplaying the unique characteristics and geography of space operations—things like gravity wells, constant movement, the energy requirements to shift from one orbit to another, and potential choke points in Celestial Lines of Communication, similar to those in Sea Lines of Communication. Perhaps Klein's next book can expand on these issues. Strategy is important. Logistics is the foundation that makes it possible, especially in space. But what Klein does, he does very well. An excellent contribution. Highly Recommended" —Choice

"Klein has made convincing arguments throughout. In what is a nascent but growing pool of academic literature, Fight for the Final Frontier is accessible to current military strategists and will help place space warfare thinking in the minds of multidomain planners. Overall, Fight for the Final Frontier presents a good thesis. It deserves a place as essential reading for any military member engaged in professional military education or indeed any staff charged with operations, strategy, or capability development." —Air & Space Power Journal

"Klein equips strategists with the necessary background to ensure strategic space access and to counter irregular warfare in space. The book is well-written, rich in theory, and well-sourced. Readers will learn a great deal from Klein’s overview of the many issues associated with space policy and irregular warfare. Indeed, one gets the impression that each chapter, even sub-sections, could in themselves constitute entire books. Fight for the Final Frontier may prod scholars to start writing." —American University's Center for Security Innovation and New Technology

"If you want to understand the national security space domain, John Klein's new tome is a must. He is one of the most insightful strategic thinks on this issue in a generation.”—Jo-Anne Sears, Partner at Velocity Government Relations

"Klein's Fight for the Final Frontier is a catalyst for future research into space warfighting. Although irregular space warfighting literature requires theoretical and empirical refinements, "the fact that irregular warfare and competitive actions in space are already everyday occurrences is not widely recognized at present" (p. 46). Klein's monograph draws attention to this neglected research area and will spring­board future discussions on how conflict in space may unfold. The text is invaluable to those developing and safeguarding space capabilities given the broad yet engaging overview of competition in space. Those involved in threat analysis and response planning will find the text an important resource for modelling the actors, threats, and dynamics inherent to space technologies and their use as a tool for strategic competition. Broadly speaking, any warfighter interested in emerging trends in war­fare will be provided invaluable situation awareness of celestial battlespaces." —Defence Studies

"At times, Fight for the Final Frontier reads more like a survey of strategy and irregular warfare than a deep dive into space warfare itself. It is a valuable overview and is useful for those Guardians (or civilians) lacking the theoretical framework for considering what conflict in space could well look like, but it feels as though space is a conceptual add-on, rather than a distinct concept. While Klein does cover some elements unique to warfare in space, such as the aforementioned RPO, satellite jamming or blinding, and intentional debris creating events, the preponderance of the discussion is not terribly different than irregular warfare on-the-ground. This is, ironically, the core value and strength of the book. Klein returns the discussion of space warfare back to a more terrestrial playing field. Warfare in space is certainly governed by unique orbital dynamics and complex physics, but it is — as he shows — not terribly different than warfare (irregular or otherwise) from that on Earth. Here, Klein’s book is a valuable step in the process of normalizing conflict in space, at least at a conceptual level. Demystifying space as an operational domain is invaluable if policymakers — both civilian and military — are to understand the role space plays in war and take necessary offensive and defensive measures.  For America’s Space Force Guardians and their counterparts in emerging allied services, such as in Australia, Japan, and the United Kingdom, Fight for the Final Frontier provides an intellectual framework for understanding that the fight on orbit is merely a zero-gravity version of Carl (and Marie) von Clausewitz’s timeless dictums. Amusingly, Klein quotes Douglas Adams’ famous dictum from Hitchhiker’s Guide to the Galaxy at the close of his book: “Don’t Panic.” It is a fitting reflection — space warfare is simply warfare." —National Security Institute