Kurt M. Campbell, chairman and chief executive of the Asia Group investment and consulting firm, was assistant secretary of state for East Asian and Pacific Affairs from 2009 to 2013.

Much has been written about the domestic consequences of growing income inequality in the United States — how inequality depresses growth, puts downward pressure on the middle class, accentuates wage stagnation and creates added difficulty paying for a college education and buying a home — but much less has been said about how inequality will affect America’s role in the world. How will the social science experiment of allowing wealth to settle so unequally between the top 1 percent and rest of the United States impact the foundations and contours of U.S. foreign policy?

In fact, there are likely to be subtle and direct consequences of growing inequality both for the United States’ international standing and its activism.

In most critical respects, the United States has helped to create and underwrite the global operating system since the end of World War II. This required a citizen’s sense of external responsibility and belief that the United States had something unique and valuable to confer to the world. Americans over these generations have regularly demonstrated in word and deed that they were prepared to bear burdens and advance ideas. Coinciding with this era was a general sense of overarching optimism that reinforced a post-World War II period of unprecedented American activism on the global scene. It is likely that as a growing segment of the population strains just to get by, it will increasingly view foreign policy — foreign assistance and military spending alike — as a kind of luxury ripe for cuts and a reduction in ambition. It is possible to see early indicators of these sentiments on the right and left, in the form of both tea party isolationism and Occupy Wall Street suspicion that corporate interests drive America’s foreign entanglements.

It is also the case that other countries have long emulated aspects of the American Way in designing their own development models. Having access to higher education, creating conditions that support innovation and allowing for greater upward mobility have all been deeply attractive qualities to many nations. But it is the construction of a durable U.S. middle class that has been perhaps most compelling to highly stratified societies across Latin America, Asia and Africa. Now, however, the United States is moving in the other direction, toward an unstable society divided between astronomically rich elites and everyone else. This undermines a critical component of U.S. soft power and is a model for societal engineering that few would choose to emulate.

It is also the case that the most recent era of U.S. exertion on the global stage has involved nearly 15 years of conflict in the Middle East and South Asia. The most important features of these largely military engagements have involved refinements in counterinsurgency technique and adaptations in military technology. A different 1 percent of the U.S. population has been primarily involved in this struggle: the U.S. military and others associated with the defense establishment. Aside from clapping when a uniformed military member greets an emotional family at an airport homecoming, the vast majority of the population has been largely unaffected by these conflicts. They neither paid for nor fought these wars.

The next phase of intense global engagement is likely to demand much more from a larger share of the population. The lion’s share of 21st-century history will play out in Asia, with its thriving and acquisitive middle classes driving innovation, nationalist competitions, military ambitions, struggles over history and identity, and simple pursuit of power. The United States is in the midst of a major reorientation of its foreign policy and commercial priorities that will draw it more closely to Asia in the decades ahead. The competition for power and prestige there rests on comprehensive aspects of national power — as much to our product and service offerings, the strength of our educational system and the health and vitality of our national infrastructure as to the quality of U.S. military capabilities. Each of these efforts require substantial and sustained longer-term investments; all face funding shortfalls due to myriad challenges. A corresponding consequence of growing inequality has been a reduction in support for these building blocks for comprehensive and sustained international engagement.

The worrisome dimensions of income inequality on the quality of domestic American life should be enough to cause us to consider enacting remedies. However, the potential negative implications on U.S. performance internationally can only add to the case. Ultimately, a sustained and purposeful American internationalism is inextricably linked to the health of our domestic life, to which gaping inequality is the biggest threat.