The United States has continued to decrease its nuclear arsenal, which will affect the reliability of the extended deterrent it has provided to its allies. One of the allies, Japan, faces an ever-changing security environment. The question then becomes this: How would Japan react to a major reduction in the U.S. nuclear arsenal? Based on three cases studies, Japan will only choose a nuclear option if the U.S. has a major reduction, and North Korea and China continue their trajectory in regard to both their nuclear and conventional forces.http://archive.org/details/normsversussecur1094552974Lieutenant, United States NavyApproved for public release; distribution is unlimited.