This book discusses the current tensions surrounding numerous maritime territorial disputes in East Asia which have become a pressing challenge for U.S. foreign policy makers. Beginning around 2005-2006, long-disputed waters in the South China Sea and, more recently, the East China Sea have become the site of increasingly aggressive behaviour from nations trying to strengthen claims to disputed areas or to explore and develop offshore energy and fishery resources. The tensions have been fed by a series of aggressive actions by maritime authorities, including harassing vessels, destroying equipment, and blockading islets and shoals. The increasing frequency of such events raises the possibility of miscalculations that could lead to overt conflict at sea. It also poses complex questions about security and U.S. diplomacy in the region, and represents one of the most complicated challenges for the Obama Administration's strategy for "rebalancing" foreign policy towards the Asia-Pacific.