In “Have We Hit Peak America,” Elbridge Colby and Paul Lettow offer a broad look at the relative decline of American power as well as thoughts on how the U.S. might leverage its considerable strengths. I found their discussion of the future global distribution of military power particularly compelling. Among U.S. policymakers, it is widely-believed that U.S. military superiority is so firmly-established as to face no serious medium-term challenge, even if the U.S. pursues deep reductions in military expenditures. Colby and Lettow remind us that this is not in fact the case.
It is often noted that the United States spends more on defense than the next 10 countries combined. But growth in military spending correlates with GDP growth, so as other economies grow, those countries will likely spend more on defense, reducing the relative military power of the United States. Already, trends in global defense spending show a rapid and marked shift from the United States and its allies toward emerging economies, especially China. In 2011, the United States and its partners accounted for approximately 80 percent of the military spending by the 15 countries with the largest defense budgets. But, according to a McKinsey study, that share could fall significantly over the next eight years — perhaps to as low as 55 percent.
I can imagine some of my interlocutors dismissing this finding, as 55 percent remains quite high. Yet raw spending obscures the fact that affluent societies have to pay more to secure trained personnel than less-affluent societies, as the opportunity cost of military service is higher in high-productivity, high-wage countries and there is a limit to the extent to which labor-intensive military functions can be outsourced. And so the difference in spending might actually overstate the capabilities of the U.S. and its (affluent) partners while understating those of potential rival states. Moreover, Colby and Lettow note that many of the technological tools (e.g., high-end sensors, guided weaponry, battle networking, space and cyberspace systems, and stealth technology) that have increased the effectiveness of U.S. forces are rapidly diffusing to rival militaries. China in particular is much closer to becoming a true peer competitor than Americans seem to think:
China, in particular, is acquiring higher-end capabilities and working to establish “no-go zones” in its near abroad in the hopes of denying U.S. forces the ability to operate in the Western Pacific. China’s declared defense budget grew 12 percent this year — and has grown at least ninefold since 2000 — and most experts think its real defense spending is considerably larger. The International Institute for Strategic Studies has judged that Beijing will spend as much on defense as Washington does by the late 2020s or early 2030s. Meanwhile, regional powers like Iran — and even nonstate actors like Hezbollah — are becoming more militarily formidable as it becomes easier to obtain precision-guided munitions and thus threaten U.S. power-projection capabilities.
Colby and Lettow aren’t simply arguing that the U.S. should maintain high military expenditures; they are also concerned with the effectiveness of U.S. military expenditures. By 2021, they report that the Defense Department expects that almost half of military expenditures will go to personnel-related costs, like the cost of wages and health benefits, as opposed to procurement, training, research and development, or operations. Even if the U.S. and China are spending roughly the same amount in the 2020s and 2030s, it seems plausible that, barring reform, the U.S. will be spending far more than the Chinese on personnel costs, thus freeing the Chinese to invest a larger share of their military budget in building advanced weapons systems.
For the most part, Colby and Lettow offer a hopeful account of how the U.S. can renew its national strength. But their careful analysis demolishes the notion that the U.S. can steeply reduce military expenditures, or leave its military personnel policies untouched, without further undermining America’s strategic position. It is true that the U.S. could decide to pivot from a policy of deep or selective engagement in Europe, East Asia, and the Gulf in favor of a role as an offshore balancer, or a role more tightly-focused on continental defense. Such an approach would mark a dramatic break with the national security policies the U.S. has pursued since the Second World War, and there are no guarantees as to what the world might look like in the wake of such a disengagement. My suspicion is that it would look much like the combustible Europe of the first years of the last century, only more dangerous.