When U.S. President James Monroe signed into law a doctrine outlining the new rules preventing European powers from colonizing and/or otherwise interfering in the political events of Latin America in 1823, the vague concept of spheres of influence was finally given true form:  Any interference in the Western hemisphere by outside powers, declared Monroe during the speech, would be interpreted as a direct threat to the United States.  Over the years, the Monroe Doctrine became the much disputed de facto declaration of U.S influence and empire over Latin America, though in the beginning Simon Bolivar thought it was an enormously positive development to give these young nation states their best shot at political sovereignty.

However, even to the casual observer, over the years the Monroe Doctrine has become rather meaningless – both to the weakening of U.S. predominance in global affairs, as well as to the rise of new (and not so new) powers like China and the European Union.