Katherine Thompson: The Republic Strikes Back

Can the United States escape the slide toward an overextended empire?

From time to time, throughout American history, the question of whether the United States should remain a republic or evolve into an empire reenters political discourse. It is upon us again, though perhaps not in the way many expected when President Trump returned to office.

Adventurism and democratic evangelism dominated American foreign and defense policy for much of the post-Cold War era. Forever wars, expanding alliance obligations, and an obsession with dominating the global commons produced limited strategic gain at immense cost. Many Americans came to associate these doctrines of the “liberal world order” with stagnation and hardship: depleted public trust, rising fiscal strain, and a growing sense that Washington attended more closely to the world stage than to conditions and interests at home.

The America First movement challenged all that. But while the second Trump administration has accomplished a number of significant doctrinal shifts toward greater realism and restraint, its actions signal a continued—and in some cases growing—imperial ambition. The pursuit of empire was unwise even when America stood alone as the world’s hyperpower and could afford to make such mistakes. In the current environment, constrained by limited resources and sharp tradeoffs, facing a peer competitor with ambitions of its own, the United States risks overextending itself in ways that could prove catastrophic for its citizens.

Though we are teetering on the edge, all hope is not lost for restoring a republic that prioritizes its citizens first. What is abundantly clear is that choosing the republic requires ruthless discipline in both doctrine and implementation. We lack that discipline now and must quickly regain it. A republic can survive the discomfort and fallout of difficult tradeoffs. It cannot survive more of the same bad decision-making rebranded under improved doctrine.

Foreign Policy in a Republic

A set of core tenets has distinguished the American inclination toward a republican foreign policy.

First, a disposition against interventionism and long-term foreign entanglement is essential. In his Farewell Address, George Washington warned that, “against the insidious wiles of foreign influence the jealousy of a free people ought to be constantly awake, since history and experience prove that foreign influence is one of the most baneful foes of republican government.” He further opposed “permanent alliances” because they subordinate national sovereignty to a foreign power’s interests, creating webs of interdependency that are difficult to untangle. Those concerns are reflected in updated form today in the new National Security Strategy, which notes, “For a country whose interests are as numerous and diverse as ours, rigid adherence to non-interventionism is not possible. Yet this predisposition should set a high bar for what constitutes a justified intervention.”

Second, when defining the national interest, it is important to start within our borders and look incrementally outward to the strategic environment. In this model, the republic is always the core from which the dynamics of the strategic environment ripple outward, posing the question to the policymaker: “How does what is happening out there hurt or help what is going on in here?” John Quincy Adams described the dangers of flipping this model around in his famous speech as Secretary of State in 1821. He said:

Wherever the standard of freedom and Independence, has been or shall be unfurled, there will her heart, her benedictions and her prayers be. But she goes not abroad, in search of monsters to destroy. She is the well-wisher to the freedom and independence of all. She is the champion and vindicator only of her own…She well knows that by once enlisting under other banners than her own, were they even the banners of foreign Independence, she would involve herself beyond the power of extrication, in all the wars of interest and intrigue, of individual avarice, envy, and ambition, which assume the colors and usurp the standard of freedom.

It is antithetical to the American republic, or any republic constituted by its citizens to serve their interests, to stand on the world stage first, and look back home second. The strategic environment becomes distorted, assaulting the senses with all manner of problems and no standard by which to assign importance.

Finally, respect for the Constitution’s separation of legislative and executive powers on matters of defense and foreign policy is essential. The principle is not an abstract one. Rather, it guards against strategic folly. James Madison illustrated this point well in a letter to Thomas Jefferson about the war power, saying, “The constitution supposes, what the History of all Govts demonstrates, that the executive is the branch of power most interested in war, & most prone to it. It has accordingly with studied care, vested the question of war in the legislative.” The ways of war evolve. The means of technology and communication advance. But the appetites, or impulses, of man are innate to the human condition. The Founders foresaw this and intentionally sought to establish guardrails to prevent the appetites from ruling.

The Temptation to Empire

The core tenets of republican statecraft are simple enough, yet American statesmen enthusiastically disregarded them over the past 30 years. The “unipolar moment” after the Cold War’s end was intoxicating and imbued U.S. policymakers with the hubris to pursue a modern, ideological form of American empire.

The policymakers of the post-Cold War era rejected the traditional dispositions against intervention and foreign entanglement and, perhaps more damning, the restraints that could prevent such engagement from ballooning uncontrollably. The wars in Afghanistan and Iraq, as well as the myriad other interventions sold as part of the Global War on Terror (GWOT), did not come with carefully crafted missions, objectives, or exit strategies. Moreover, as both the Bush and Obama administrations repeatedly redefined the enemies, the scope of the military campaigns, the levels of diplomatic and humanitarian engagement, and the definition of success, the legislative branch sat largely on the sidelines. Congress engaged in no serious conversations about revoking or amending authorities or funding until the 2018–19 calls for ending U.S. support to the Saudi Coalition in the war in Yemen. The trillions of dollars spent on the GWOT-era conflicts did not produce a coherent and sustainable counterterrorism strategy, did not establish sustainable democracies, and distracted the U.S. from preparing for the emerging great-power rival coming around the corner.

The rejection of restraint went far beyond the GWOT. Since 2000, the North Atlantic Treaty Organization (NATO) has accumulated 14 new member nations. In theory, as proponents of expansion have argued, a larger alliance means a more powerful military deterrent. In practice, as has been well documented by now, decades of underinvestment by allies left the U.S. shouldering the bulk of NATO’s costs and defense expectations, which thus increased far faster than any actual capacity gains.

The GWOT interventions, NATO expansion, and other projects to deepen America’s global relationships set the expectation that the United States could respond at the drop of a hat to any bat signal coming from anywhere in the world. The demand for U.S. support to Ukraine is the latest example. While the U.S. had no formal treaty obligations to Ukraine and Congress took no vote to enter a conflict on Ukraine’s side, the U.S. began providing military and foreign aid in 2014 and dramatically increased direct material support from U.S. weapons stockpiles in 2022 after the start of the Russian invasion. The executive branch acted in purely reactionary fashion, reflexively elevating Ukraine’s needs to the first-order priority. Rather than provide a check or voice of caution, the legislature enabled the executive through multiple billion-dollar supplemental appropriations. Concern for the impact on American citizens and U.S. short- and long-term strategic flexibility was placed well below the interests of a foreign nation, or never considered at all, in the minds of many of our nation’s decision makers.

Time after time, Congress has allowed the president to usurp its exclusive or shared role in U.S. foreign and defense policy. From making war to making treaty commitments, the executive branch is now fully accustomed to bypassing Congress. Presidents of both political parties started new wars in the Middle East and Africa under the auspices of existing authorizations or a dubiously expansive reading of the powers of the president as commander-in-chief under Article II. Documents that further entangle the U.S. globally, like the Paris Climate Accord or the Joint Comprehensive Plan of Action (JCPOA), which clearly constitute treaties, become law by executive fiat and impose commitments on the United States without Senate advice and consent. Congress sits back, protecting itself politically while the republic suffers structurally.

Doctrinal Strength, Decisional Shortcomings

At the outset of the second Trump administration, expectations were high for a genuine and pivotal shift in American grand strategy. The expectation was that the United States would adopt a narrower and more disciplined definition of the national interest. The promise was realism and prioritization: an acknowledgment that the unipolar moment had ended, that tradeoffs could no longer be avoided, and that the preservation and welfare of the republic and its citizens had to return to the center of strategic thinking.

In the formal doctrine of the National Security Strategy and National Defense Strategy, the administration accomplished a meaningful course correction. Those documents demonstrate both an understanding of the political forces that returned President Trump to office and a broader recognition that the assumptions underpinning the post-Cold War order no longer hold.

The National Defense Strategy is especially significant in moving the United States past the failures of overextension in defense commitments and military interventionism, defining rebalanced allied relationships and a revitalized defense-industrial base as priorities which directly support America’s core national interests. It assesses the nation’s defense priorities looking from the homeland out into the strategic environment. Protecting the homeland in our near abroad comes first. Action by China in the First Island Chain is highlighted as the greatest threat capable of penetrating American security at home if unchecked.

This is a strategy which grapples with the structural realities inherited from the last three decades, squarely rejects the modern quest for American empire, and makes the health of the republic the core priority.

But doctrine alone is insufficient. Grand strategy ultimately succeeds or fails in implementation, not publication. On that score, the second Trump administration increasingly presents an obstacle to the project it promised to advance. The United States is running out of both bandwidth and luck.

For decades, America’s advantages allowed policymakers to postpone difficult strategic choices. Military dominance, healthy munitions stockpiles relative to the scale of active conflicts, reserve-currency status, and the lack of a peer competitor were taken for granted and gave politicians the false confidence to accumulate global commitments without full consideration of the consequences. That margin for error is shrinking. Demands for America’s attention and entrenchment across the Middle East, Europe, the Western Hemisphere, and the Indo-Pacific compete and trade directly against one another. At present, the fiscal and resource constraints are moving quickly from theoretical to mathematical, at which point neither political charisma nor savvy messaging can obscure them.

Reality is politically agnostic and will eventually become unavoidable. The political leaders in charge when the breaking-point crisis hits will find themselves with few good options and a lot to explain.

The central shortcoming of the second year of President Trump’s second term is not an intellectual failure to recognize the dangers of overextension. It is an instinctual inclination to revert back toward the same tendencies that the doctrinal shift was meant to correct.

The clearest and most prominent example is the administration’s decision to go to war with Iran. The strategic contradiction is impossible to ignore. A prolonged conflict with Iran consumes massive quantities of munitions, operational attention, naval assets, intelligence resources, and political bandwidth at precisely the moment the administration’s own doctrine argues such resources must be preserved for higher-order priorities. The decision went against the administration’s own recognition that the Indo-Pacific and homeland defense should remain the nation’s principal focus and came despite the well-known readiness and industrial base constraints the administration was already encountering in the Ukraine problem set.

The same contradictions are increasingly visible in the Western Hemisphere. The administration is correct that the near abroad matters profoundly to American security and sovereignty. A republic-centered grand strategy should naturally prioritize stability and deterrence within the Western Hemisphere over distant theaters abroad. But the “how” is again most important. Reverting to interventionism and regime change because it is the most familiar precedent lacks strategic clarity.

Even initiatives intended to solve structural problems reveal the lack of commitment to implementing stated strategy. The Prioritized Ukraine Requirements List (PURL) Initiative attempts to rebalance the burden of support for Ukraine by asking European NATO allies to assume financial responsibility for further military aid. Conceptually, this aligns with the administration’s strategic doctrine. Yet PURL is exacerbating U.S. defense-industrial base constraints by placing more demand on a broken system that will not be able to meet U.S. and European demand simultaneously. The U.S. defense-industrial base does not lack demand. What it lacks is structural integrity to support demand, and the policy guidance that U.S. requirements must take first priority over allies and partners. We are seeing this already as an adjacent consequence of the Iran war. The U.S. is essentially bumping European allies out of the queue for high-value munitions systems which Europe intended to purchase for Ukraine because expenditure in Iran and stockpile shortages pose a real threat to U.S. readiness that cannot be ignored.

Taken together, these examples expose the vulnerability of the current moment. Washington increasingly understands the need for strategic restraint in theory while continuing to struggle with it in practice. The gravitational pull toward empire did not disappear simply because policymakers began announcing republic-centric doctrine. It remains deeply embedded within the political, military, and bureaucratic instincts of the American government.

Implementing a doctrine that reprioritizes our republic imposes the temporary pain of ripping off the band-aid. But at least it is honest. Prolonging the inevitable pain unnecessarily harms both the United States and its allies, and also leaves more room to backslide into the comfortable but perilous status quo ante.

A Somber Hope

The Trump administration cleared an important intellectual hurdle. After decades spent trapped in the flawed assumptions of the early 1990s, it forced Washington to confront the realities of scarcity and strategic limits. Prioritization has claimed its place in the conversation. The disconnect between that progress in theory and the continued errors in practice only underscores the challenge of turning the ship of state.

The window for course correction remains open, but barely. Not only preserving doctrinal gains, but also translating them into better policy and a lasting shift from empire back toward republic will require a rapid increase in discipline from our political leaders. Agreeing on republican virtues is much easier than renouncing imperial ambitions.

Katherine Thompson is a senior fellow in defense and foreign policy studies at the Cato Institute. She previously served as deputy senior advisor to the Under Secretary of War for Policy and as national security advisor to Senator Mike Lee and foreign policy advisor to Senator Josh Hawley.