After 1945 only the Soviet Union could assume the role of a major potential challenger to the US in international affairs. However, unlike some earlier “world powers” that did not ensure complete American dominance subsequently. While its warWar in Vietnam could be explained as a direct consequence of the earlier French defeat, America failed to realize that military dominance could not always be generated, nor great wealth create that. However, before the present century it was not evident that, in some contexts, the Constitution itself might become the central inhibitor of the exercise of power in some contexts. Unlike other federal systems, the US has constitutional rules that make their major reformReforms both difficult and complex. Moreover, the range of issues that political systems must now address, including Artificial Intelligence and Climate Change, has greatly expanded and has complicated the pursuit of advantage internationally.