The United States and South Korea enjoy many benefits from close security cooperation but the relationship, although not currently endangered, is shifting. The paramount challenge in the short term is ensuring that the two countries stay in lockstep in dealing with North Korea. Sustaining the relationship for the long haul, however, will require a focused effort to adapt it to new global and domestic conditions. Recent attention has been given to the appropriate nature, size, and configuration of U.S. forces deployed in Korea. These central questions deserve heavy emphasis but the answers provided will remain vulnerable to domestic political currents in both countries without affirmation of a larger common purpose. Other important issues include a joint agreement to move the U.S. garrison out of Seoul, South Korea's role within the alliance, and the South Korean desire for a more "equal" partnership. The U.S. should examine whether restrictions on weapons sales to Korea might be relaxed in certain areas and whether the bar on permissible technology transfers might be raised, while creating opportunities for South Koreans to help shape a new security relationship that gives them a greater sense of ownership. For its part, South Korea must act like an equal partner if it wants to be treated as one. At its core, this means taking its own responsibility for the health of the alliance. While continuing to address such "future of the alliance" issues, the U.S. also needs to address a broad set of issues relating to management of the alliance today.