This issue of Asia Policy features a roundtable on lessons learned in different regions from the Russia-Ukraine war; articles on the intersection of Northeast Asia’s aging demographics with a rise in security concerns, the ripe potential for Japan–South Korea cooperation on maritime initiatives in Southeast Asia, and the patterns of maritime policing in the South China Sea among the sea’s disputing claimants; and a book review roundtable in which participants discuss the evolving influence of demographics and societal norms in Japan’s security policy.