This article subjects the notion of the San Francisco system to critical scrutiny. It identifies the origins, evolution, and various meanings attributed to the term. In its original sense it meant the Northeast Asian security order that was based on the US-Japan alliance. The argument here is that its current meaning as a comprehensive system of security was a later accretion and cannot be supported by the facts. The article then analyzes the contemporary challenges to the system as understood in its original meaning, examining the consequences for the system of a rising China and arguing that since the Senkaku/Diaoyu Islands clash between Japan and China in September 2010, the US-Japan alliance has been strengthened. China's actions have made the alliance more important for Japan, and the system will continue.