But the Communist victory in Vietnam did lead to the rest of Indochina going Communist, as the domino theorists predicted, and it played a role in the Soviet advances across the Third World during the rest of the 1970s – from Ethiopia and Mozambique to Afghanistan and Nicaragua, with various other proxy wars thrown in for good measure. ~Ross Douthat

Well, this may be a bit of quibbling, but something close to half of Indochina/southeast Asia (Thailand and Burma) did not turn communist, and instead of turning red Indonesia under Suharto became a (rather nasty) anticommunist bulwark and Malaysia was not seriously affected.  The Pacific Rim allies were basically fine after Vietnam.  For domino theory to have been right, many more dominoes would have had to be knocked over.  For all the warnings of ever-advancing communism, communism acquired those strategic gems of Cambodia and Laos and then contested for the various backwaters (no offense, Nicaragua) mentioned by Ross.  Having just detached China from the Soviets, America could reasonably afford to risk setbacks in such vitally important places as Mozambique.  (One problem of withdrawing from Iraq is that we have yet to have a foreign policy crew interested in or capable of pursuing anything like a China-style detachment of a formerly hostile regime.) 

Fights over influence in Latin America and Africa were not new in the post-Vietnam era (see Egypt, Zaire, Angola), and Soviet-backed Cuban mischief overseas had already been going on for a while.  Soviet aggression became much greater in the wake of the Iranian Revolution.  At the time, that was a huge loss.  It was the failure of the Carter Administration to cope with the challenge in Iran that helped embolden the Soviets into invading Afghanistan (similarly, it was Carter’s failure that damaged the Democrats’ reputation on foreign policy leadership immeasurably more than anything related to ending the war in Vietnam, contrary to the popular myth circulated by some GOP talking heads).  A comparable Iran-like setback, a really serious blow to our strategic interests, would be an expressly jihadist revolution in Pakistan, which would make any consequences of an Iraq withdrawal as a matter of U.S. strategic interests look small and irrelevant.  Indeed, as a matter of U.S. strategic interests–and it is this, and not, I’m afraid, the casualty count that traditionally governs great power foreign policy–the consequences of an Iraq withdrawal will be damaging but hardly devastating.  In Realpolitik, the loss of a Cambodia or a Laos is not all that important.  (Someone will say that Iraq and many of its neighbours are different and much more important, to which I say: re-read Luttwak.)  Since domino theory was meant to describe the strategic consequences of the failure to contain communism in southeast Asia by military intervention, it does not say much for domino theory that every strategically important country in Far East that should have turned communist did not actually turn.   

Domino theory related to communism was an updated version of old British paranoia dating to the Great Game: today the Russians have Tashkent, tomorrow they will have Delhi!  To the extent that the British were fairly crazy to worry about the Tsar’s armies marching over the Khyber Pass and across northern India to Delhi and through Baluchistan to the sea, the domino theory was also pretty crazy.  In its time, it was also dreadfully respectable, the sort of serious thinking that foreign policy intellectuals love. 

It was also the product of ignoring a Kennan-like approach to international affairs and accepting that the enemy was actually driven by a transnational ideology that could traverse boundaries of nationality and culture without difficulty and which would present a united, pro-Soviet front against the West.  The detachment of China, and the Sino-Vietnamese war that followed shortly after the fall of the South were proof that this idea was wrong in its core assumptions about international communism.  It was proof that Kennan’s attention to nationalism and nationalist policies in understanding communist states was the fundamentally correct analysis of how these states acted.  Wild-eyed notions of universal communism spreading around the world like wildfire (or was it fire in the minds of men?) once the fire was lit somewhere proved to be wrong, because they vastly overestimated the appeal of transnational ideology when compared to the much stronger draw of nationalism.  Having mistaken nationalist revolutionaries for true-believing commies, domino theorists could never grasp the implications that the domino theory could not happen in the real world because of the barriers created by ethnic, cultural and religious difference.  There is comparably mistaken thinking today inasmuch as those predicting the worst following a U.S. withdrawal believe that some unified global jihadism exists and will sweep all before it.  Having mistaken the particular interests of various state and non-state actors for a more or less unified jihadist (or, God help us, Islamofascist) front, these people see disastrous post-withdrawal outcomes that are unlikely to occur.  They think we are in an “ideological struggle.”  In fact, we are not, or at least it is not of the kind they are describing.  Their analysis is necessarily going to be flawed as a result.