In hindsight, one is tempted to wonder, How could we have been so blind? If the Truman administration was committed to defending South Korea, and could see that it might get attacked, why did it withdraw the 45,000 troops it already had there, against the wishes of the South Korean government and the better judgment of commanders on the ground? We were inviting the Communists to invade. Indeed, that is precisely how Kim Il Sung saw the matter, and that is how he argued it to his Soviet masters. But the matter was not quite so simple from the Communist point of view.
There is still debate over whether Stalin ever gave his assent to Kim’s invasion plans; but it seems clear that if he did assent, it was only with considerable hesitation. It wasn’t that Stalin had any interest in peace or in avoiding conflict with the West. He was causing conflict everywhere, and, as George Kennan had observed, he had to do so in order to enhance the internal security of the regime. But Stalin understood better than Western leaders that, despite the overwhelming military advantage he then possessed, and despite the fact that the entire organizing principle of Soviet society was militarism, the real strategic advantage of Communism was not military but political. And he likely understood better than anyone in the West that the great strength of democratic constitutional order was not political but military. In fact, the democratic system’s ability to generate vastly greater military power than any other system had been obvious since the armies of the French Revolution went about destroying the military establishments of ancient kingdoms all over Europe as if all it took were one blow of Napoleon’s breath. That is why Soviet strategy during the Cold War always used political subversion rather than military confrontation in challenging democracy.
The question of Korea was if anything even more complicated from America’s point of view. In Deterrence in American Foreign Policy: Theory and Practice (1975), Alexander George and Richard Smoke squarely face the question of why Truman would have withdrawn U.S. forces from South Korea rather than leave them in place as a deterrent. “The general theory of deterrence,” they write, “does not contain very useful criteria for indicating when a state should attempt to apply deterrence to protect a weaker country. The answer to this question can be determined only by a country’s foreign policy, not by deterrence theory.” The United States was still thinking in terms of the last war — a global general war. Our government had only begun to understand the importance that small, strategically peripheral countries like Korea might have in our overall strategic defense. As George and Smoke note:
Truman’s decision to oppose the North Koreans was not motivated by a sudden discovery that the strategic importance of Korea to American military security was greater than had been calculated earlier. Rather, the administration now assessed the expected danger to U.S. interests from allowing the North Koreans to take over South Korea on the basis of a much broader and more complex calculus than the earlier strategic criterion.
The U.S. government was only starting to grasp that its Achilles’ heel was not military but political.
The period from 1945 to 1950 was one of very rapid change, and the U.S. government took time to assimilate what was happening. With the fall of Nationalist China to the Communists, the critical U.S. bastion in the Far East became Japan. China now had to be contained as part of a Soviet system that was emerging as a global power. It was still only dawning on the American government that the challenge of Communism would be existential and global; that the new enemy had great military power, and even greater political and psychological strengths; and that the Soviets would not be able to achieve internal security except by exporting insecurity to the rest of the world.
In April 1950, just two months before the outbreak of the Korean War, a top-secret strategic assessment known as NSC-68 — which would prove to be one of the seminal texts of U.S. strategy in the Cold War — showed that the U.S. was beginning to understand the new situation it faced. It was a long document, full of military facts and figures, but the one key idea was this: “A defeat of free institutions anywhere is a defeat everywhere.” The key strategic insight of this mostly military document was therefore not military at all, but rather political.