George Friedman places recent US-Vietnam engagement within the history of balance-of-power diplomacy going back to the 1960s, in order to make a simple but compelling point. US relations with the USSR, China, and Vietnam have been only trivially inflected by ideological differences:
… look at the whole story and see how little ideology matters. The entire story is one of three Marxist regimes hostile to each other, and a Western capitalist regime using that hostility to balance the power. […] From the point of view of geopolitical analysis, the unimportance of ideology in all that happened is clear. The importance of the nation-state, regardless of its official ideology is equally clear. None of these four nations behaved as their ideology demanded. All behaved as their national interest did. […] This is why I find geopolitics an enormously more important method for understanding the world than beliefs and principles. These may matter in personal life. But the Marxism that defined Ho Chi Minh, Mao Zedong and Leonid Brezhnev – and they were very much believers – could not resist geopolitical imperatives. And therefore, the president of the United States went to a Marxist country and set the stage for arming it. This should not surprise us.