Real-life diplomacy reveals, as Lord Palmerston, twice British prime minister (1855-8, 1859-65), famously put it: "We have no eternal allies, and we have no perpetual enemies. Our interests are eternal and perpetual, and those interests it is our duty to follow." Over the decades the Palmerston Principle has proven relevant to other countries in their foreign relations, including the United States.
In our case, of course, we are notorious for our swoons of idealism but we can be brought down to earth by changes in reality. Case in point: the astonishing evolution of U.S. relations with the Socialist Republic of Vietnam.
Vietnam today, like so much of Asia, is on a roll. Although its per-capita income is less right now than even the Philippines', it is growing. Its population is three times that of Peru, a quarter more than France's, more than double that of Canada's, and almost four times that of Australia's. Its economic reforms are starting to release its workforce from the prison of socialism.