In today’s interview, I spar with Harriet Moynihan over the application of international law to cyberattacks, a topic on which she has written with clarity and in detail. We disagree politely but profoundly. I make the case that international law is distinct from what works in cyberspace and is inconsistent with either clarity or effectiveness in deterring cyberattacks. Harriet argues that international law has been a central principle of the post-1945 international system and one that has helped to keep a kind of peace among nations. It’s a good exchange.