On its face, Defense Secretary Chuck Hagel’s recent announcement that the U.S. Army is to be downsized to pre-World War II levels makes eminent sense. In fact, many consider such a move to be long overdue. The United States today faces no geopolitical threat comparable to that posed by Nazi Germany and Imperial Japan in the 1940s or the Soviet Union during the Cold War, while America’s long stretch of fighting its “wars of choice” in Iraq and Afghanistan is now ending under President Obama’s leadership. Why, then, is it already conventional wisdom that the Pentagon’s 2015 budget will be opposed in Washington for being overly austere? The answer is that even if international circumstances have changed dramatically over the past seventy years, so too has America.

Owing its origins to the Continental Army formed in 1775, the United States Army is the only branch of the armed forces as old as the U.S. itself. For most of its history, the army has waxed and waned in size roughly in line with the level of threat faced by the republic that it helped to found. For the most part, this meant a small standing army. At times, however, particular exigencies (including, to be sure, some of America’s own making) meant that the army ballooned in size: in 1812, 1846, 1861, 1898, 1917, 1942 and 1968, for example.

Historically, the shrinking of the U.S. Army has been a reliable concomitant of its periodic increases. Following the Treaty of Ghent to end the War of 1812, for example, Congress cut the size of the army by four fifths, from 62,674 to 12,383. In 1821, even this number of soldiers was halved. After the American Civil War, during which conflict the number of Union soldiers topped one million, President Andrew Johnson pressed ahead with reducing the army to numbers actually below prewar levels. In the immediate aftermath of World War II, President Harry Truman cut the size of the army from 8.2 million soldiers in 1945 to under 600,000 by 1950—demobilizing an average of around 29,230 soldiers per week across the five-year period—and would probably have continued to slash numbers if it had not been for worsening geopolitical conditions in Eastern Europe and Northeast Asia culminating in the outbreak of the Korean War.

That the U.S. ever was able to expand and contract the size of its army with such remarkable precision is entirely because, for most of its history, America’s political class has had little to gain—and, indeed, much to lose—from maintaining a military establishment surplus to requirements. Quite simply, the U.S. electorate was opposed to a large standing army for most of the 175 years that followed American independence. Opposition to the garrison state has been as much a part of America’s national ideology as it has been a product of ingrained preferences for low taxation.

This consensus, however, has been dead for nearly seventy years. Ever since the onset of the Cold War in the late 1940s, at least one of the nation’s two parties—and frequently both of them—have had strong economic, electoral and thus political incentives to maintain an expansive military establishment, irrespective of the level of threat in the international system. As political scientist Ben Fordham has argued, even the initial Cold War military buildup was designed (by necessity) as much to satisfy key domestic constituencies as it was to meet the menace posed by the Soviet Union. Over the intervening seven decades, the sectional interests whose livelihoods depend upon unrelenting massive defense expenditure have become entrenched, their concerns represented in the highest echelons of government. A huge peace-time military establishment is now normal.

Hagel’s proposals envisage an army of around 450,000 personnel, considerably less than the 520,000 servicemen and servicewomen that are under arms today—116,000 less, in fact, than the post-9/11 peak in army personnel witnessed in 2011. Although much of the current discussion is being couched in the language of fiscal restraint (particularly with regards to military pay and benefits), the Pentagon’s move to resize the army is motivated by hard-headed strategic calculations at least as much as it is by budgetary ones. The nature of the threats facing the U.S. today, the Pentagon is arguing, simply does not require a permanent force of half a million active-duty military personnel.

Instead, the downsizing of the army should be seen alongside parallel proposals to transfer dollars from funding assets that exclusively counter old threats (e.g. the Cold War-era U-2 spy plane) to ones that promise to meet current and future military-strategic demands. Officials stress, for example, that there will be no cuts to cyberwarfare programs or special operations. While the A-10 “Warthog” will be decommissioned in recognition of its sole suitability for providing close air support in the context of ground-based mass engagements, funding for the more versatile F-35 fighter jet will be protected.

Not all of this strategic rebalancing will be opposed, but the proposal to slash the size of the army stands out as something likely to draw a torrent of criticism. To be sure, a leaner army will wash with most Democrats—elected officials and grassroots activists alike. This is because the modern Democratic Party is a coalition that mostly brings together a patchwork of groups with little to gain from investment in the military. The short- to medium-term future of the Democratic Party is much more to do with domestic renewal than it is military spending.

Yet pundits are correct to state the obvious that the administration’s plans will have a torrid time with congressional Republicans. The Republican Party of 2014 has deep partisan interests in maintaining high levels of military spending—particularly in its southern heartlands (where a disproportionate amount of the army’s bases are located) and in areas where arms manufacturers are significant employers. Once a bastion of Democratic support and a key driver of Kennedy-era military Keynesianism, the South’s militarism now finds expression in the platforms of hawkish Republicans. Even the famously noninterventionist, small-government Rand Paul has a hard time coming out against large military bases on U.S. soil. “I’m not saying don’t have any [overseas military bases]”, Paul is quoted as saying, “I’m just saying maybe not 900. I mean, I’d rather have one at Fort Campbell and Fort Knox…than one in Timbuktu.” Fort Campbell and Fort Knox, of course,
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Beyond narrow partisan interests, there is a second reason that Republican lawmakers and candidates for office can be counted on to rail against the administration’s attempts to economize: entitlements. In contemporary U.S. politics, entitlement reform has become the position issue par excellence—that is, an issue that unambiguously distinguishes the parties from one another, reliably helping voters to differentiatebetween candidates at election time. Especially in the present context of tightened belts, Democrats portray themselves as defenders of the social safety net while Republicans trumpet their credentials as the only ones willing to make “difficult choices” (a euphemism, mostly, for spending cuts) that will rescue the nation’s finances. Talk of cuts to defense spending provides Republicans with an invaluable point of comparison with what they perceive to be out-of-control entitlement spending. Texan Congressman Michael McCaul already has lambasted the administration for sacrificing U.S. military readiness “on the altar of entitlements.”

In this regard, history is repeating itself. In 1993, Senator John McCain’s scathing report of post-Cold War defense policy (“Going Hollow: The Warnings of Our Chiefs of Staff”) was used by Republicans both to inspire support for sustained investment in the military and to galvanize opposition President Clinton’s ambitious domestic agenda. The intimation then, as now, was that the two spending priorities were intimately connected; that spending on entitlements and investment in the military were locked together in a zero-sum relationship. In the late 1970s, too, the Reaganite charge against Jimmy Carter’s Democrats was that Carter had presided over a dangerous weakening of the post-Vietnam national-security establishment while plundering the public finances to bankroll a massive expansion of the federal government.

In the modern era, it simply is impossible for decisions about the size of the U.S. military to be made with reference to external conditions alone. If it ever did, partisan politicking no longer stops at the water’s edge. Questions of grand strategy and national security policy—the size of the army included—are as much to do with distributive politics as they are with the dangerousness of America’s external environment. The U.S. Army today is no nimble tool to be wielded by leaders towards the sole end of protecting the republic. Instead, it is an elephantine fixture of the political and economic landscape. It will not easily be reduced.

Peter Harris is a Ph.D. candidate in the Department of Government at the University of Texas, Austin, and a graduate fellow at the Clements Center for History, Strategy and Statecraft.