U.S. President Barack Obama is set to visit Australia and Indonesia later in November after months of diplomatic efforts aimed at improving perceptions of the U.S. commitment to the Asia-Pacific region, largely to counter growing Chinese power. This is coming as maritime security issues have begun to dominate regional affairs, with China taking a particularly aggressive stance in the South China Sea. Part of the U.S. re-engagement includes the intent to reshape the East Asia Summit (EAS) into a U.S.-led regional security institution. This year's EAS, set for Nov. 18-19 in Bali, will thus serve as a gauge for Washington to demonstrate its commitment to Asia-Pacific maritime security affairs. Beijing, which has been carefully developing its strategy for Southeast Asia over the past two decades, understands the challenges posed to it by the United States' re-entry into the region, particularly to its South China Sea plans. The possibility of a new power balance will test both China's ability to achieve its long-term goals and its relations with countries on its periphery. China's rapidly expanding economic influence in past years has enabled it to improve relations with neighboring states and gradually take a leading role in Southeast Asia, turning it into a testing ground for its strategy of soft-power diplomacy in an important sphere of influence. Beijing's strategy largely has been based on economic cooperation, such as Chinese investment and aid to individual countries and increased trade through bilateral arrangements and regional mechanisms. One example of this is the free trade area that went into effect between China and members of the Association of Southeast Asian Nations (ASEAN), the most extensive set of trade and investment agreements between the two. As Southeast Asia is one of the few regions that generally marks trade surpluses with China, Beijing has attempted to convince ASEAN countries that they will benefit from China's economic growth with its economic clout. China has been making progress with a charm offensive in the region, building political and security influence that has been facilitated by high-level military visits and arms sales, a longstanding policy of noninterference in other countries' internal affairs, and, notably, a decadelong period of relative neglect by the United States. Beijing has used this leverage to gain an advantage in the South China Sea. It has raised its profile in regional security facilities, such as the EAS and ASEAN Defense Ministers Meetings, and cultivated relations with mainland ASEAN countries, such as Laos and Cambodia, to prevent maritime disputes from gaining prominence in these regional organizations. It also has begun bilateral negotiations over maritime issues such as energy exploration, shunning third-party involvement and dealing with individual countries to prevent them from adopting a unified stance. However, China's increasingly aggressive moves to stake its maritime claim have shifted Asian perceptions, leading to growing tensions between China and other claimant countries such as Vietnam and the Philippines. The rapid modernization of the Chinese military and the expansion of its blue-water strategy — especially its aggressive moves in the South China Sea since the beginning of 2011 — also have caused disquiet among China's Southeast Asian neighbors. These countries have begun both to cooperate regionally to counter Beijing's dominance in the South China Sea and to call for outside powers, particularly the United States, to do the same. With Washington's renewed interest in the region, Beijing sees considerable uncertainty in its maritime and Southeast Asia strategies. In particular, China expects the upcoming EAS to officially institutionalize a multilateral mechanism to address South China Sea issues — running directly counter to its attempts to deal with these issues bilaterally. However, direct confrontation between China and the United States would come at the expense of both China's domestic situation and regional stability. Moreover, the United States' physical distance from the region, as well as heavy U.S.-Chinese economic and political interactions in other areas, means that both sides have more reasons to cooperate than they do to press their agendas for the South China Sea. Meanwhile, Beijing has seen the need to adopt proactive diplomatic efforts, such as enhancing traditional economic ties with ASEAN countries and indicating that it would be open to leading regional discussion forums for negotiating South China Sea issues. Such gestures may be appealing to Southeast Asian claimant countries; no matter how far the United States goes to re-engage in the region, these countries' economic futures will be inextricably linked to China. China has proposed a set of principles that would govern future EAS discussions, called the Declaration of the East Asia Summit on the Principles of Mutually Beneficial Relations. In it, China calls for an integrated East Asian community and enhanced Chinese-ASEAN interdependence through economic ties. At the same time, as the United States' Asia-Pacific strategy becomes clearer, it provides an opportunity for Beijing to clarify its role in regional strategic affairs, and particularly to remedy the increasing disunity between its economic strategy and security strategy. As part of this, the United States' stated intention of leading the EAS means China likely will try to support ASEAN as the premier regional bloc, something that ASEAN countries likely will be interested in as they try to avoid being hostages for either side in the increasing U.S.-Chinese competition. It remains to be seen whether the U.S. plan for Asia-Pacific re-engagement will shift the balance of power in the region. Nonetheless, China will need to take a much more active stance to maintain its position.