From the Taliban to Hezbollah, armed nonstate actors and civil warfare have dominated the US national security debate for much of the last 20 years. Yet, most analysis shares a critical underlying assumption: that non-state actors fight very differently than states do.In Nonstate Warfare: The Military Methods of Guerillas, Warlords and Militias (Princeton UP, 2021), Dr. Stephen Biddle argues that those ideas are not just misleading but dangerous. Through a careful review of five nonstate actors, Dr. Biddle shows that state and nonstate military methods vary more by degree than by kind. Still, degrees do matter.To predict how “conventionally” or “unconventionally” a nonstate actor will fight, Dr. Biddle develops a theory reliant on two key variables: the stakes leaders perceive in a conflict and the strength of a nonstate actor’s institutions. The greater either variable, the more that actor will fight like we expect states to: defending and seizing ground, concentrating forces, employing heavy weapons, and implementing a stratified theater of war.On the episode, we talk about all that and more. I ask Dr. Biddle about the flaws in status quo theories of nonstate military methods, how the lethality of the modern battlefield creates similar tactical incentives for state and nonstate militaries, and what the implications of his theory are for international politics writ large and US defense planning in particular.Note: At the very end, I ask Dr. Biddle, who spent time on Defense Department analytical staffs focused on Afghanistan, for his opinion on the rapid advance of the Taliban. Please note that he is a private citizen and his statements do not represent the official view of the government. The podcast was also recorded on 7/13, two days before the fall of Kabul.Dr. Biddle is a Professor of International and Public Affairs at Columbia University, a member of the Arnold A. Saltzman Institute of War and Peace Studies, and Adjunct Senior Fellow for Defense Policy at the Council on Foreign Relations. In addition to his academic work, Dr. Biddle has served on the Defense Department’s Defense Policy Board, on General David Petraeus’s Joint Strategic Assessment Team in Baghdad in 2007, as a Senior Advisor to the Central Command Assessment Team in Washington in 2008-9, and as a member of General Stanley McChrystal’s Initial Strategic Assessment Team in Kabul in 2009, among other government advisory panels and analytic teams.John Sakellariadis is a 2021-2022 Fulbright US Student Research Grantee. He holds a Master’s degree in public policy from the School of International and Public Affairs at Columbia and a Bachelor’s degree in History & Literature from Harvard University.