Over the course of world history, the largest changes to the cultures of peoples have come from either brutal conquest, education, or a combination thereof. As the Hoover Institution's Thomas Sowell showed in his book Conquests and Cultures, conquests that result in cultural change have typically involved the violent overthrow of the existing ruling class, the forceful imposition of the conquerors’ culture on the vanquished, and prolonged military occupation of the conquered land. Such was the methodology of the Normans in England, the Ottomans in the Balkans, and the Spanish in the Americas.

In its recent occupations of Afghanistan and Iraq, the United States used violence to remove the ruling class from power but did not hold the new rulers or their peoples at gunpoint while demanding conformance to American cultural norms. The draconian techniques of Hannibal and Cortes have never been especially popular in the United States. The pressures of omnipresent media and international opinion have, in any case, made them inconceivable as options for the U.S. government.

Some of the Americans responsible for planning the military expeditions to Afghanistan and Iraq hoped to transform these countries into liberal democracies in a few years through the installation of democratic institutions and free market capitalism. But this kinder, gentler form of conquest did not yield the cultural changes required for liberal democracy. The Americans did not impose severe punishments on Afghan and Iraqi leaders every time they resisted elements of liberal democracy that clashed with their traditional cultures. When Hamid Karzai ignored American advice to award key jobs based on merit, or when Iraqi Prime Minister Nouri al-Maliki seized control of governmental entities intended to limit executive authority, the Americans did not hang them, or even cut off funding to their governments.

The presence of American forces did compel Karzai and Maliki to heed some American demands, but that advantage dissipated as the American forces departed. American politicians chose not to maintain a large military presence in either country for the long term, as had been done in Germany and Japan after World War II and in South Korea after the Korean War. In those countries, half a century of American occupation had provided security, political guidance, and cultural influence in enough depth to ensure permanence.