CAMBRIDGE – Donald Trump, the Republican Party’s presumptive US presidential nominee, has expressed deep skepticism about the value of America’s alliances. His is a very nineteenth-century view of the world.
Back then, the United States followed George Washington’s advice to avoid “entangling alliances” and pursued the Monroe Doctrine, which focused on US interests in the Western Hemisphere. Lacking a large standing army (and with a navy that in the 1870s was smaller than Chile’s), the US played a minor role in the nineteenth-century global balance of power.
That changed decisively with America’s entry into World War I, when Woodrow Wilson broke with tradition and sent US troops to fight in Europe. Moreover, he proposed a League of Nations to organize collective security on a global basis.
But, after the Senate rejected US membership in the League in 1919, the troops stayed home and America “returned to normal.” Though it was now a major global actor, the US became virulently isolationist. Its absence of alliances in the 1930s set the stage for a disastrous decade marked by economic depression, genocide, and another world war.