East Asia has again become a top priority for America following a decade of preoccupation with terrorism. Much has changed: China is now an economic, technological and military power second only to the United States. This ascendance poses new challenges for U.S. friends and interests in the region and raises the strategic stakes for the United States. Though its nuclear doctrine emphasizes deterrence and no first use, China is fielding second-generation nuclear forces that can overwhelm U.S. missile defenses and strike the United States. Of greater concern, China is developing capabilities to attack satellites and computer networks on which U.S. prosperity and security depend. For all its power, the United States is increasingly vulnerable to strategic attack.