In this third installment of CNAS’ Maritime Strategy Series, Dr. John Lee of the University of Sydney discusses political and diplomatic tools to impose costs on bad behavior in maritime Asia as part of an overall strategy encompassing military and non-military tools. Dr. Lee argues that present legal and multilateral mechanisms are insufficient to constrain assertive behavior by rising powers, China in particular. As a first step toward a more robust architecture, Dr. Lee recommends that the United States and other regional powers –Australia, Japan, the Philippines and Vietnam – ought to explore the possibility of formalizing a Code of Practice (CoP) as declaratory policy regulating behavior guiding all disputes in both the East and South China Seas. Such a concept could then be promoted to other regional states such as Singapore, Indonesia and Malaysia, while leaving the door open for China. Among other benefits, a Code of Practice instrument would help generate collective pressure, including by key great powers, to challenge coercive behavior and define sorely needed rules of the road.