Nuclear strategy has become a core concern in the U.S.-Japan alliance. North Korea is the immediate trigger for Japanese anxiety, but similar uncertainties lie just beneath the surface when Japan contemplates China as well. U.S. assurances are needed – both to Japan and to potential adversaries that need to be deterred. Most important, however, is a “back to basics approach” for the U.S. and its alliance partners. Changing international circumstances and evolving domestic politics oblige Washington and its allies to focus on fundamentals of strategy to ensure that alliances have the foundation – the common worldview – that will allow them to survive and thrive in a new strategic environment.