The Illusion of Isolationism

By Michael E. O’Hanlon

Monday, January 05, 2026

 

Citing his contempt for allies and his hostile attitude toward immigration, analysts and commentators often paint U.S. President Donald Trump’s leadership style as a throwback to the isolationist ways of the nineteenth-century United States. This argument is half right. The essence and emphasis of Trump’s national security policy does hark back to a number of early U.S. presidents, including James Monroe, Andrew Jackson, James Polk, William McKinley, and, at the turn of the twentieth century, Theodore Roosevelt. But none of those presidents were isolationist, and neither is Trump. The similarities, to the extent they exist, are of a different type, and they have more to do with maximizing American power than minimizing the U.S. role in the world.

 

Understanding Trump in historical perspective may at least provide modest solace for those who see his foreign policy as radical and unprecedented. Doing so should also remind Americans that they have always been highly audacious on the global stage. That can be a good thing, when the United States is resolute in defense of interests and allies. It can also, however, get the country into trouble—as it has in the past—if Americans forget their proclivity for muscular action and delude themselves into thinking they are somehow an inherently peaceful people.

 

The United States has poked its nose into international affairs since its earliest days, waging a quasi war with France and its sponsored pirates in the Caribbean from 1798 to 1800 and facing Barbary pirates in the Mediterranean from 1801 to 1815. It spent the nineteenth century expanding its territorial borders while also becoming increasingly active in the Pacific Ocean and Asia. After a few land wars and a more serious buildup of its navy, by the turn of the twentieth century the United States was consciously entering the club of great powers, sizing its naval buildups by reference to other powers’ capabilities. Washington did try to stay out of European wars, but it was still dragged into World War I in 1917. The only time the United States can be said to have truly attempted a form of isolationism was in the 1920s and 1930s, when it dismantled most of its military capabilities and disengaged from global affairs. But even though U.S. grand strategy may have tended toward isolationism in that period, U.S. defense strategy still progressed, with new concepts and technologies developed for carrier warfare, aerial combat, and amphibious assaults. As the United States got wrapped up in World War II, those advances proved crucial. Once the war ended and the Iron Curtain began to descend, proponents of American isolationism became and remained rare.

 

Like almost all of his predecessors, Trump has revealed himself to be a highly assertive internationalist rather than an isolationist. Since taking office in January 2025, he has claimed to have resolved eight global conflicts; engaged in persistent efforts to end the war in Ukraine; recommitted to NATO at the alliance’s 2025 summit; conducted a brief but significant bombing of Iranian nuclear sites; advanced a modest but real buildup of the U.S. military; and, most recently, captured Venezuela’s president and taken a regrettably lethal approach toward suspected drug smugglers in and around Venezuelan waters. Increasing American power is thus the centerpiece of his national security policy, paralleling nineteenth-century expansionist ideals and early-twentieth-century naval and industrial ambitions.

 

Fortifying American power is not in itself a bad thing. But it is not enough to succeed in building a peaceful world or to protect the United States in today’s world. And the mere fact that Trump’s national security policies have various historical precedents hardly guarantees their success. What worked in the nineteenth century may not be effective in the twenty-first. Moreover, despite a generally strong track record, U.S. policymakers have made plenty of mistakes when devising strategies for national security throughout the history of the republic. Despite what many early presidents did to build up the United States, they failed to establish a sustainable national security policy that would prevent the two world wars. And even though Trump has thankfully not dismantled any American alliances to date, his nationalist policies, including tariffs, have undermined the sense of common purpose that has bound the Western world for 80 years and prevented World War III—at least so far.

 

MANIFESTING IT

 

The history of U.S. foreign policy and defense strategy has been almost exclusively one of assertion. For 101 years after George Washington was inaugurated as the first U.S. president, in 1789, until the Battle of Wounded Knee effectively ended armed battles with Native Americans in 1890, the United States pursued a grand strategy of expansionism, taking what had been a sliver of a country along the Atlantic coast and turning it into a continental power. The military forces and operations that supported this grand strategy—a mix of federal forces and militias—were usually quite small in scale, numbering at most in the low tens of thousands, except during the Civil War. But this was not because the United States was pacifist or isolationist; it simply did not need anything larger. These small forces were ruthlessly efficient in how they operated, winning hundreds of battles against Native American tribes, often through divide-and-conquer techniques, and a war against Mexico from 1846 to 1848.

 

As the nation grew, so did the United States’ confidence. In 1803, U.S. President Thomas Jefferson bought, in a peaceful exchange, what would become roughly a third of the continental United States from France in the Louisiana Purchase. Consolidating control over those lands took several decades, but by 1812, the United States was already bold enough to declare war against Great Britain. Washington had legitimate grievances against the British, most notably over the impressment of American sailors onto British ships, but the fact that a young United States was prepared to fight the world’s reigning naval hegemon over the issue spoke volumes about its strategic character and assertiveness. So did the U.S. posture toward the British colony of Canada, which Washington tried to bring into the fight on its side, toying with the idea of farther northward expansionism, although in the end the attempt proved too militarily ambitious.

 

Then came the Monroe Doctrine of 1823, which warned Europe against intervening in the Western Hemisphere. That a still mostly pre-industrial and militarily weak United States would claim the exclusive right to supervise geopolitics in all of the Americas was a breathtaking display of chutzpah. Although its practical implications were modest, it revealed an American spirit and ambition that are hard to square with the concepts of isolationism or strategic minimalism.

 

Over the next few decades, the United States continued to consolidate and extend its control of western lands, including through the infamous Trail of Tears, which forcibly relocated the many Native Americans remaining in the eastern third of the country to its center, during the administrations of President Andrew Jackson and Martin Van Buren. Then, from 1846 to 1848, there was the U.S.-Mexican War—probably the biggest and most audacious land grab in American history, even if it was nicely dressed up in the concept of “manifest destiny.” What began as a modest territorial dispute led Congress to declare war on Mexico and, after the United States captured Mexico City, demand the vast swaths of land that now make up the present-day American southwest, including California, in the ensuing peace deal. There was certainly nothing isolationist or defensive about the war or the peace agreement that ended it.

 

TO INFINITY AND BEYOND

 

By 1890, the United States had become a continental power. Next it was to become a great power. To be sure, Washington still tried to avoid land wars in Europe. It kept its army small, although big enough to defeat Spain in the Spanish-American War of 1898—gaining control over Cuba, Guam, Puerto Rico, and the Philippines in the process.

 

Despite its acquisition of the Philippines, Washington did not wind up pursuing territorial imperialism on a large scale. But its navy was developing the capability to compete on the world stage. Waves of construction starting in the 1880s meant that by the time World War I began, the U.S. Navy had the third-highest tonnage of warships in the world. The key figures of the late nineteenth century who drove this process—the naval strategist Alfred Thayer Mahan, Roosevelt, McKinley, and others—saw naval power as crucial for the United States’ standing in the world. The United States had found a taste for a much more expansive foreign and defense policy.

 

At the beginning of the twentieth century, the Root reforms and Dick Act—named for U.S. Secretary of War Elihu Root and Senator Charles Dick, respectively—restructured and strengthened the U.S. Department of War, including the National Guard. In 1904, the Roosevelt Corollary to the Monroe Doctrine stipulated that not only was the Western Hemisphere closed off to outside colonial intervention, but Washington would also have an active say over any key political and strategic matters that it chose in the neighborhood. The corollary was used to justify numerous U.S. interventions in Latin America in the following decades, including in Mexico and the Caribbean, as well as U.S. support for secessionists in Colombia, which led to the establishment of Panama and ultimately paved the way for the U.S. construction of and sovereignty over the Panama Canal. (Trump, for his part, has just echoed the Roosevelt Corollary with his own Trump Corollary to the Monroe Doctrine, as declared in the December 2025 National Security Strategy.)

 

The quarter century that began with the Wilson administration, during World War I, and ended with the U.S. entry into World War II demonstrated how impractical American attempts at isolationism, even if rare, really are. In 1916, President Woodrow Wilson campaigned for reelection on staying out of World War I—even after German U-boat torpedoes killed many hundreds of Americans crossing the Atlantic, including on the Lusitania, a British ocean liner sunk in 1915. But despite wanting no part of the war and viewing French and British imperialism as one of its underlying causes, in 1916 Wilson signed the Big Navy Act, which led to another substantial round of American naval shipbuilding that allowed the United States to wade more deeply into the realm of great-power competition. By the spring of 1917, driven by the resumption of unrestricted German submarine warfare as well as the interception of the Zimmermann Telegram, in which Germany tried to persuade Mexico to attack the United States, Wilson had changed his mind about staying out of the conflict and persuaded Congress to declare war. By the latter part of 1918, the United States had built up a military of four million men, two million of whom were in Europe when the war ended in November. The United States was not yet the arsenal of democracy; in fact, most of the weapons its troops used in the war were manufactured in France. But it was rapidly becoming the most powerful country on earth.

 

After World War I, U.S. policymakers did engage in true isolationism, in the 1920s and 1930s. As the U.S. Senate rejected Wilson’s case for ratifying the League of Nations treaty, which was aimed at preventing future war, it passed the Washington Naval Treaty, which gave cover to a naval drawdown during the 1920s as the United States pulled back from the world for the first time in its history. The isolationism of that day gave rise to, among other things, the dismantling of most of the U.S. Army, as well as the Neutrality Acts in the mid-1930s, which prevented Washington from even selling arms to the world’s major democracies. The advent of World War II, however, brought this short period of American isolationism—less than ten percent of the country’s history—to an end.

 

STICK TO THE STATUS QUO

 

During Trump’s first term and campaign for reelection, it did seem as if he might change the essence of U.S. grand strategy and defense to a form of minimalism. He complained about the excessive size of the defense budget, questioned what the NATO and U.S.-Korean alliances were for, doubted whether Ukraine mattered to American interests, and advocated greater prioritization of matters close to home, notably along the U.S.-Mexican border.

 

Perhaps some of these ideas will resurface, and indeed, border issues and immigration have been a central focus of Trump’s domestic and foreign policy. But Trump’s second term has been characterized much more by maximalism than any form of minimalism. His administration has brokered peace negotiations around the world, if not as successfully as he claims; championed NATO, if offending European partners in the process; authorized the use of force against Iranian nuclear facilities and Venezuela’s sitting president; and advocated for greater U.S. defense spending. He has dismantled zero American alliances. The most dramatic pullback of forces that the Trump administration has proposed to date concerns a single U.S. Army brigade in Romania—several thousand troops out of a total of around 100,000 in Europe.

 

Trump’s actions have thus dispelled any illusion that he is an isolationist, and given the history of the United States, no one should have expected him to be. Apart from a few U.S. presidents in the interwar period—Warren Harding, Calvin Coolidge, and Herbert Hoover—isolationism really does not reside in the DNA of American grand strategists. Indeed, Wilson’s about-face on World War I serves as a good reminder that U.S. involvement in Eurasian conflict is not a matter of simple preference. Wilson wanted to avoid war just as Trump now does. It is indeed commendable to abhor violence and to want to avoid traps like the wars in Afghanistan, Iraq, and Vietnam, as Trump asserts he does. But preventing great-power war over the past 80 years has required a system of American alliances and forward military deployments that the country would be remiss to discard now. Perhaps Trump will eventually reach this conclusion, but it is too soon to really be sure.

 

Trump’s internationalism—and the similarity in his thinking to that of former presidents such as Jackson, Polk, McKinley, and Roosevelt—does not mean that his often impulsive and idiosyncratic decision-making style is a positive thing for U.S. foreign policy. But in his approach to national security, Trump is not nearly as unprecedented a figure in American history as is sometimes alleged. His philosophy centers on the pursuit of national power, not simply as the main priority but as the overwhelming fixation. Yet if not leavened with a more inclusive vision that takes the legitimate interests of other countries into account, such a simplistic pursuit of national interest can fail catastrophically. What may have worked for the first half of the country’s history—ethics aside—did not work thereafter, and it is unlikely to begin working now.