In his classic Cold War history, Strategies of Containment, John Lewis Gaddis explains the reasoning of NSC-68: Even Kennan — then a major proponent of balance-of-power thinking — agreed that “insecurity could manifest itself in psychological as well as physical terms, as the Western Europeans’ demands for American military protection had shown. And psychological insecurity could as easily develop from the distant sound of falling dominoes as from the rattling of sabers next door.” In their own equivalent of trying to win “hearts and minds,” the Soviets were trying to convince world opinion that the democratic order was doomed because of its intrinsic weakness, and if they had succeeded, we might in fact have been doomed. “The implications were startling,” writes Gaddis. “World order, and with it American security, had come to depend as much on perceptions of the balance of power as on what that balance actually was.”
The Cold War marked the emergence of a new force in international relations: world opinion. For a democracy, the implications were and are fundamental. It turns out that democracies boil down to popular self-government even in the field of foreign policy. The Founding Fathers were keen to protect our foreign policy from the vicissitudes of public opinion, but no democratic order can or should protect the policy from public opinion itself. The exertion of strategic power by a democracy depends on public opinion. When the United States projects great power abroad, it is a projection of public opinion, translated into strategic power. And by the same token, public opinion is the great limiting factor on the otherwise virtually unlimited military power of modern democratic states. We saw that in Iraq: An invasion force of 60,000 troops was able to destroy an army five times larger with minimal casualties in a matter of weeks. The ensuing counterinsurgency was hard fought, but public opinion in the U.S. and around the world arguably came closer to defeating the war effort than an insurgency which never achieved sufficient scope or power to have any real chance of winning.
So why did Truman withdraw U.S. forces from South Korea in 1949? The unanswered questions that Korea raised for U.S. strategy in the pre-war period — chiefly, how vital was our interest there, and how far should we be ready to go in defending it — made it almost inevitable that the U.S. would make grave strategic mistakes, and indeed it did.
Once the war broke out, those unresolved questions fed right into the policy failures of the Korean War itself: the inability to define an attainable war aim, the inability to gain consensus for a coherent strategy, the inability to avoid conflict at the highest levels of the administration.
In Afghanistan, Obama is facing all of these challenges. What is the relationship of Afghanistan to our broader defense strategy? What is our broader defense strategy? What are our war aims in Afghanistan? Are we really trying to fashion a lasting democratic government and functioning security forces out of one of the most primitive societies on earth? Or are we merely trying to prevent al-Qaeda from establishing training bases there again, which it apparently has little interest in doing now that it has them in many other places? Is Afghanistan our problem, or is our problem really Pakistan?