I am delighted to present the latest publication from the Stimson Center’s Japan Program. Key Challenges in Japan’s Defense Policy is the seventh volume of Views from the Next Generation, an annual collection of policy briefs that offer recommendations for the most significant challenges facing Japan and its partners today. This edition benefits from the diverse expertise of five leading and emerging scholars, who share with us fresh insights on Japan’s defense policy. The topics they cover—ensuring a human resource base for the military, deterring attacks from new technologies, balancing budget constraints with emerging threats, and maintaining partnerships amidst political changes—are pressing questions for not only Japan but states around the world. As governments design policy to adapt to novel domains like outer space, cyberspace, and the electromagnetic spectrum, the acceleration and complexity of threats mandate new thinking. Here we look to nuanced analysis from up-and-coming e...