250 Years of American Foreign Policy

In late 1776, months after the United States declared its independence from Britain, Benjamin Franklin arrived in France. By then, the inventor, scientist, writer, and political thinker was a household name. Once in France, Franklin saw his face everywhere—on medallions and rings and tobacco boxes. He even watched as fashionable French ladies adopted his headdress, a fur cap style they called the “coiffure à la Franklin.”

Franklin was arguably the most famous American in the world at the time; historians have called him the first American celebrity. But members of French society could not say for certain why he had come.

In truth, he was there on a covert mission. Franklin had been sent to secure French support in his country’s war with Britain. In doing so, he was performing a new role for his country. He wasn’t just the first American celebrity. He was also the first American ambassador.

His efforts to secure an alliance marked a crucial first step in the history of U.S. foreign policy. Over the following two-and-a-half centuries, the United States grew from a loose union of former colonies to the global superpower it is today. Along the way, its leaders have faced a vast array of foreign policy challenges and responded to those challenges in equally various ways. But throughout the country’s history, foreign policymakers in the United States have grappled with recurring questions that would likely have been familiar to Franklin himself: When should the United States involve itself in foreign conflicts? How should the country balance its ideals with its interests? And what obligations, if any, come with the country’s growing power? The answers have shifted over time—sometimes dramatically so—but the questions have endured.

Read on to explore some of the most essential moments in that foreign policy story.

After independence, the United States seeks to protect its interests and avoid entanglements overseas. Challenges to U.S. sovereignty, however, complicate the young country’s path forward.

One year after the first shots of the Revolutionary War rang out, delegates from the thirteen American colonies meet in Philadelphia and sign the Declaration of Independence. The document marks the birth of a new nation, built on Enlightenment ideas of individual liberty and equality. As the colonies fight to make that declaration a reality, they seek allies, forming the country’s first international relationships. The Continental Congress sends a team of diplomats, including Benjamin Franklin, to France, where they ultimately secure an alliance. France proves to be a critical partner in the defeat of Britain, contributing weapons, ammunition, supplies, and even military officers to the American cause.

As George Washington takes office as the first U.S. president, revolution erupts in France. Britain soon unites with other European powers against France. Americans are divided on what to do, and so is Washington’s cabinet. Secretary of State Thomas Jefferson believes the country should support its French ally—and their shared republican values. Secretary of the Treasury Alexander Hamilton argues that the United States should avoid a war with Britain that could jeopardize U.S. security and economic stability. Washington ultimately issues a Neutrality Proclamation, announcing that the United States will remain impartial toward European powers. The idea of avoiding entanglements with European powers, reinforced in Washington’s 1796 farewell address, establishes a precedent that U.S. presidents will follow for more than a century.

Despite Washington’s Neutrality Proclamation, Britain continues to threaten the United States. On land, Britain maintains its military forts in the American West. At sea, it interferes with U.S. trade, seizing ships and sailors. With the two countries seemingly on the brink of war, Washington sends Chief Justice John Jay to Britain to reach a deal. The United States has little leverage in the negotiations; its goal is simply to stabilize relations with Britain and increase trade. The resulting treaty accomplishes those goals. But it fails to stop the seizure of American goods and sailors. The treaty is widely unpopular and deepens an emerging rift between political parties. Critics see it as a betrayal of France. Even supporters feel it gives up too much for too little. Although the treaty avoids a war with Britain, U.S. relations with France deteriorate. The two countries will fight a so-called Quasi-War at sea four years later.

Just like the United States, France has territorial ambitions in the Americas. France acquires Louisiana—a large territory between the Mississippi River and the Rocky Mountains—from Spain in 1802. It also acquires the port city of New Orleans. Worried that France will use its control of the city to block Americans from accessing the Mississippi to trade with the world, the United States sends representatives to France with an offer to buy the city. France, however, is struggling to maintain control of its Caribbean possessions and now faces renewed war with Britain. To the surprise of U.S. diplomats, France offers to sell not just New Orleans but also all of the Louisiana Territory. With the purchase, the United States doubles its size and eliminates a possible threat from a European power. It is free to settle new territory; however, expansion will mean uprooting dozens of Indigenous tribes from the land they call home.

As Britain and France clash in Europe’s Napoleonic Wars, the United States again tries to stay neutral. But the British Royal Navy continues to seize American ships, cargo, and sailors. In 1812, the United States declares war. Supporters see war as a way of cementing respect for American sovereignty. Still, the British have the military advantage. They blockade and raid the U.S. coast, even occupying the nation’s capital and burning the White House. But the United States proves more formidable than expected at sea. The war ends with a treaty in which neither side gains major concessions. At home, the war deepens divisions between the states, as some bemoan its economic harm to their regions. Overseas, however, the war improves Europe’s assessment of the United States as a whole. By fighting the British Empire to a draw, the country gains respect from European powers. Meanwhile, major victories against British-aligned Indigenous tribes set the stage for further westward expansion.

Through purchase, negotiation, and conquest, the United States expands its territory across the North American continent. By the turn of the twentieth century, its influence stretches beyond the continent as well, spanning from the Caribbean to the Pacific.

U.S. leaders fear that European powers will help Spain retake colonies that had declared independence from Spain during the Napoleonic Wars. In his 1823 message to Congress, President James Monroe says the United States will not interfere with any existing European colonies in the Western Hemisphere. But Monroe also warns that the United States will regard any effort to create or reinstate colonies as a threat to U.S. security. Monroe knows the United States cannot back up his threat. He calculates, however, that Britain—then the world’s most formidable naval power—will prevent further European colonization so that it can continue to trade with Latin America’s independent states. Still, the Monroe Doctrine becomes a long-standing principle of U.S. foreign policy upon which future presidents will expand.

As their numbers grow, American settlers look to move west. They petition the federal government to remove Indigenous tribes that stand in the way of expansion. President Andrew Jackson takes up their cause, urging Congress to pass the Indian Removal Act. The law authorizes Jackson to negotiate with the tribes, offering them land west of the Mississippi if they leave their current territories. Facing threats and bribes, some Indigenous leaders sign removal treaties. Others, like the Cheroke and Seminole tribes, resist—leading to war and forced expulsion. In carrying out the removals, Jackson ignores a Supreme Court ruling that says Indigenous tribes are sovereign nations. Under Jackson, the United States will forcibly remove nearly fifty thousand Indigenous people, clearing the way for settlers to further expand U.S. territory.

American settlers spread across the continent, reaching as far as the vast Oregon Territory in the Pacific Northwest. The United States and Great Britain both claim ownership of the territory, which is valuable for its fur trading and access to new routes across the Pacific Ocean. Initially, the United States and Britain jointly occupy the territory—but by the 1840s, the Oregon settler population comes to greatly outnumber the British presence. Expansionists in Washington, DC, push for full control of the territory, calling for war if necessary. President James K. Polk—despite having campaigned for the White House on the promise to take all of the Oregon Territory for the United States—seeks a diplomatic solution. Ultimately, the United States and Britain negotiate the Oregon Treaty, which divides the territory in two along the forty-ninth parallel, paving the way for the states of Oregon and Washington, and leaving Britain what will become British Columbia.

The annexation of Texas in 1846 brings the United States into a territorial dispute with Mexico. Texas, which had seceded from Mexico a decade earlier, had claimed expansive boundaries, which Mexico disputed. (Mexico did not officially recognize Texas’s independence, either.) After Mexico rejects a U.S. bid to buy the land, Polk moves troops into the contested territory, triggering war. The United States invades Mexico, eventually seizing Mexico City. Defeated, Mexico makes huge concessions: it recognizes Texas as part of the United States, with the borders that Texas claimed, and cedes over half its territory—including sections that will make up most of Arizona, all of California, and parts of Colorado, as well as Nevada, New Mexico, Oklahoma, Utah, and Wyoming.

Russia has maintained small settlements in Alaska since the late eighteenth century, but it comes to view the territory as unprofitable and too distant to administer effectively. After a costly defeat in the Crimean War and new geopolitical interest in Asia, Russia looks to sell Alaska. Uninterested in selling to Britain, its main enemy during the Crimean War, Russia negotiates a deal with the United States to sell Alaska for $7.2 million (roughly 2 cents per acre). U.S. proponents of the deal argue that Alaska gives the United States access to additional resources and ports to boost U.S. trade with Asia and will pressure British Columbia to join the United States. Critics decry the purchase as a waste of money on a frozen wasteland. At first, Americans scarcely use the territory, and British Columbia reacts to the deal by seeking to join Canada. But the discovery of gold in Alaska in the 1890s will spark a surge of interest in Alaska and vindicate the deal’s supporters. 

A revolt against Spanish rule in Cuba generates widespread American sympathy, as well as concern that a prolonged conflict could disrupt U.S. economic interests in Cuba. When an American battleship, the USS Maine, explodes in Havana under mysterious circumstances, Americans are outraged, blaming Spain for the incident. Congress authorizes U.S. military support for Cuban independence, triggering war. U.S. forces easily defeat Spain, which is forced to give up not only Cuba but also other colonial territories in the Caribbean and Pacific. The United States had ruled out annexing Cuba as part of its war aims, but it takes control over Guam, the Philippines, and Puerto Rico. Meanwhile, it also annexes Hawaii, which a committee of mainly American residents and businessmen had advocated for since leading the overthrow of Hawaii’s monarch years earlier. In the span of a single year, the United States acquires overseas territories stretching from the Caribbean to the Pacific, marking a departure from its continental past.

In Venezuela, European powers mount a blockade to force the payment of foreign debts. Worried that such interventions are a threat to U.S. regional dominance, President Theodore Roosevelt announces a major reinterpretation of the 1823 Monroe Doctrine. He claims that if Latin American countries cannot maintain order or pay their debts, the United States has the right to act as an “international police power” to prevent European intervention. The 1823 Monroe Doctrine had provided the justification for keeping Europe out of Latin America. Roosevelt’s corollary transforms that policy into justification for U.S. intervention in the region. Roosevelt applies the doctrine immediately, taking control of customs houses in the Dominican Republic in 1905. Although he will order only one other military intervention during his seven years in office, his successors will send U.S. troops into several Caribbean and Central American countries repeatedly over the next three decades.

Now an industrial powerhouse, the United States grapples with uncertainty over its role in a fracturing world. Two global conflicts vault the country onto the world stage as a leading military and economic power.

As war devastates Europe, the United States initially declares itself neutral. But the country continues to trade with all belligerents, a policy that favors France and the United Kingdom. Long-standing cooperation between banking houses in New York and London deepens, facilitating French and British purchases of American-made goods. The U.S. economy, which had previously entered a recession, suddenly booms. To Germany, U.S. neutrality looks like a myth. The Germans initially respond with submarine attacks against U.S. merchant vessels and cruise liners, before agreeing in 1916 to limit what types of ship they will attack. In 1917, however, facing a crushing naval blockade, Germany resumes unrestricted submarine warfare. A month later, Americans learn that Germany has offered to help Mexico reclaim the territory it lost seven decades earlier if Mexico attacks the United States. Those factors ultimately prompt the United States to enter the war. The full weight of U.S. industrial capacity and fresh soldiers helps tip the balance toward Allied victory.

After World War I, President Woodrow Wilson travels to Paris to negotiate the peace settlement and persuade the Allied powers to create an international organization that will prevent future wars. Wilson prevails. The Treaty of Versailles ends the war and establishes the League of Nations, which aims to preserve peace through collective security, diplomacy, and arms reduction. But Wilson runs into fierce opposition when he submits the treaty to the Senate. Roughly a dozen senators oppose the League of Nations on principle, arguing that it will involve the United States in conflicts that have no bearing on U.S. interests and will limit the country’s ability to respond to conflicts that do. More senators support the League of Nations in theory but demand revisions to protect U.S. sovereignty. Wilson refuses to accept any changes to the treaty. Ultimately, the Senate rejects the treaty and with it the League of Nations. The United States never joins, weakening the organization’s effectiveness. Meanwhile, the idea of collective security remains politically toxic in U.S. politics for the next two decades as the country seeks to avoid entanglements outside the Western Hemisphere.

The onset of the Great Depression in 1929 devastates the U.S. economy. American farmers, facing growing international competition and falling prices, call on the government for protection. To boost prices, President Herbert Hoover proposes a limited agricultural tariff, or a tax on imported farm goods. Protectionists in Congress, however, push to include increased tariffs on industrial products as well. The resulting Smoot-Hawley Tariff Act places sweeping tariffs on over twenty thousand products. Hoover signs the bill, despite warnings from economists that the legislation will deepen the Great Depression. Their prediction comes true. U.S. trading partners—including Britain, Canada, and France—respond by imposing retaliatory tariffs. Global trade collapses, with U.S. exports falling by nearly half within three years. The Smoot-Hawley tariff becomes a symbol of misguided protectionism. In 1933, Congress attempts to revive U.S. exports by passing the Reciprocal Trade Agreements Act (RTAA), which gives the president authority for three years to negotiate bilateral, reciprocal tariff reductions of up to 50 percent without congressional approval. The RTAA lays the groundwork for U.S. efforts to negotiate tariff reductions in the following decades.

Germany invades Poland in September 1939, triggering World War II. The United States initially remains neutral. Congress, fearing that war in Europe is imminent, has passed Neutrality Acts to limit trade with belligerent nations. Though President Franklin D. Roosevelt initially supports those acts, he increasingly pushes Congress to relax the policy. He tells Americans that the country should be the “arsenal of democracy” in the fight against fascism. Congress ultimately endorses the idea, passing the Lend-Lease Act, which authorizes Roosevelt to lend or lease war supplies to any country he deems “vital to the defense of the United States.” That aid proves critical to the Allied victory. In 1941, after the Japanese attack the U.S. naval base at Pearl Harbor—and after Germany declares war on the country—the United States joins the conflict. U.S. troops fight in Europe, North Africa, and the Pacific. Meanwhile, U.S. scientists develop the first atomic bomb, which the United States drops on the Japanese cities of Hiroshima and Nagasaki to force Japan’s surrender in 1945.

Even as World War II is being fought, Roosevelt looks ahead to what the postwar world should look like. To prevent a return to the economic chaos of the 1930s, U.S. and British officials meet for two years to discuss a design for the post–World War II international economic system. In 1944, representatives from forty-four countries gather at Bretton Woods, New Hampshire, to finish that work. Two core international financial institutions emerge from the conference: the International Monetary Fund (IMF)—which will work to stabilize the international monetary system—and the International Bank for Reconstruction and Development (which will become the World Bank)—to help finance postwar reconstruction and long-term economic development. Because of its economic dominance, the United States holds significant sway in both institutions. The Bretton Woods system will ultimately shape international economic relations for decades and establish U.S. economic leadership in the world from 1945 forward.

During World War II, Roosevelt works to revive Wilson’s vision of an international organization body that will prevent conflict and promote peaceful cooperation. In the final months of the war, representatives from fifty countries gather in San Francisco to establish what becomes the United Nations. Learning from the failure of the League of Nations, the UN Charter creates both a General Assembly, where all countries have equal status, and a Security Council with restricted membership and the ability to authorize military action against aggressors. The five victorious powers in World War II—the United States, Britain, China, France, and the Soviet Union—each have permanent membership on the Security Council with a right to veto its decisions. The United Nations presides over several subsidiary organs, involving economic, humanitarian, and social concerns.

The United States emerges from World War II into a tense competition with the Soviet Union defined by ideological rivalry, nuclear tensions, and proxy conflicts. The Cold War unfolds globally, leading the United States to unprecedented levels of international involvement.

Though the United States and Soviet Union were allies during World War II, each becomes suspicious of the other after the war ends. Efforts to expand Soviet influence in Europe and the Middle East alarm U.S. officials. In February 1947, Britain informs the United States that it lacks the means to continue aiding Greece and Turkey. In Greece, communist rebels with Soviet support are seeking to topple the government. In Turkey, the Soviets pressure the country for joint control over the strategic waterway connecting the Black Sea to the Mediterranean Sea. Fearing communist expansion, President Harry S. Truman calls on Congress to provide aid to Greece and Turkey. He declares that the United States will assist “free peoples” fighting against “totalitarian regimes,” arguing that the spread of communism would “undermine the foundations of international peace and hence the security of the United States.” Under what becomes known as the Truman Doctrine, the United States now defines its interests globally.

European economies remain devastated from years of war. Many countries are vulnerable to communist influence. Fearful that the battlefield victory for which U.S. troops fought so hard to win could soon be lost, Truman directs Secretary of State George Marshall to devise a plan to aid Europe. The plan stresses that European nations have to work together to develop an effective recovery program before the United States provides funding. The Truman administration works closely with members of Congress in developing the Marshall Plan. It argues that U.S. aid is not charity but an effective way to repel communist influence and expand markets for U.S. goods. Congress needs less convincing after the Soviet Union denounces the plan and forbids its East European satellites from participating. Afterward, Congress approves the Marshall Plan. Over the next four years, the United States provides $13.2 billion in aid (roughly $180 billion in today’s dollars) to sixteen West European countries. That aid jump-starts Western Europe’s economy, blunts Soviet influence, and deepens U.S. economic and political ties with Europe.

As Cold War tensions rise, leaders in the United States and Western Europe grow concerned about expanding Soviet influence. A Soviet-backed communist coup in Czechoslovakia and a blockade of West Berlin escalate those fears. One month after the coup in Czechoslovakia, Belgium, France, Great Britain, Luxembourg, and the Netherlands pledge to defend each other if one is attacked. But alongside the Truman administration, they recognize that such a military alliance will succeed only if the United States joins. In 1949, the United States joins Canada and ten European countries to form the North Atlantic Treaty Organization (NATO). NATO members agree that an attack on one must be treated as an attack on all. In the following years, the United States stations U.S. troops and equipment in Europe, affirming its commitments to mutual defense. In 1955, Moscow forms its own regional alliance with East European countries—the Warsaw Pact—cementing Europe’s split between Western and Soviet spheres.

The United States is now committed to containing communism around the world. In Asia, Korea becomes an early battleground. After U.S. and Soviet forces liberated Korea from Japanese rule in World War II, the peninsula remained divided between a communist, Soviet-backed North and a U.S.-supported South. In 1950—after the Communist Party takes power in China—North Korean troops invade the South, fueling fears that another country will fall under communist rule. The United States immediately intervenes to support South Korea and wins UN backing for its military operations. (The Soviet Union is absent for the vote, having boycotted the Security Council over its refusal to give China’s new Communist Party government a seat.) UN forces drive the invaders back across the thirty-eighth parallel that divides the two Koreas. They then advance deep into the North. But as they near the Chinese border, China intervenes, forcing the UN troops to retreat. The fighting settles into a stalemate near the original dividing line. In 1953, an armistice halts the combat. The war claims an estimated two-to-three million lives and leaves Korea divided.

In 1959, Fidel Castro overthrows a U.S.-backed dictator and takes power in Cuba. Castro soon aligns with the Soviet Union and declares Cuba a socialist country. In 1961, the United States launches the Bay of Pigs invasion, a disastrous plan to send Cuban exiles to oust Castro. In the wake of the attack, Cuba strikes a secret deal with the Soviet Union. The Soviets will station nuclear-tipped missiles in Cuba to deter future U.S. attacks and to give the Soviet Union a counter to U.S. missile deployments in Turkey and Western Europe. In October 1962, a U.S. spy plane discovers the missile sites, triggering a dramatic standoff. President John F. Kennedy orders a naval quarantine of Cuba while negotiating with the Soviet Union. Eventually, the Soviets agree to remove the missiles. In exchange, the United States publicly pledges not to invade Cuba. Privately, it promises to remove U.S. missiles from Turkey within six months. The crisis marks the closest the two powers will come to a nuclear exchange. It leads them to create a hotline for crisis communication and to move toward arms control negotiations.

In 1954, a communist-led insurgency forces France to abandon colonial rule in Vietnam. The peace settlement leaves the country divided. In the North, a communist government rules. In the South, the United States backs an anti-communist government that soon faces a Northern-backed communist insurgency. The United States initially sends military advisors to train South Vietnamese forces, but U.S. involvement subsequently escalates. In 1964, the United States launches retaliatory air strikes after a U.S. destroyer reports being attacked by North Vietnamese patrol boats. As the military situation deteriorates in South Vietnam, the United States deploys combat troops and begins a sustained bombing campaign against North Vietnam. Victory remains elusive, however, and opposition to the war grows in the United States as the conflict spills over into neighboring Cambodia and Laos. In 1973, the United States negotiates an end to the war. Two years later, North Vietnam invades South Vietnam and quickly conquers the country. The war leaves more than two million Vietnamese civilians and roughly fifty-eight thousand Americans dead. The Vietnam War splits the bipartisan Cold War consensus in the United States as many Americans question U.S. military intervention overseas.

After the Bretton Woods Conference in 1944, major currencies were fixed to the U.S. dollar, which was convertible to gold at a fixed rate. But high U.S. spending during the Vietnam War, as well as depleted gold reserves, growing inflation, and global export competition, put mounting pressure on the U.S. dollar, leading President Richard Nixon to close the so-called gold window in 1971, ending foreign countries’ ability to exchange dollars for gold at a fixed rate. Markets face turbulence as currencies begin to float, or fluctuate in response to the foreign exchange market, and governments scramble to craft new rules for international finance. Many countries attempt to preserve fixed-exchange rates, but by 1973, major currencies begin floating against each other based on market forces. Many smaller economies continue pegging to the dollar for stability. By 1976, a new approach emerges. Global financial stability will no longer depend on the stability of individual exchange rates. Instead, each country—with help from the IMF—will work to stabilize its domestic economy, helping in turn to stabilize the global economy. That approach marks the beginning of the modern international monetary system.

For more than four decades, Germany had been divided into two countries: East Germany and West Germany. In Berlin, a wall through the city formed both a literal and symbolic front line between communist and democratic blocs. But by the late 1980s, the Soviet Union’s control over its European satellites begins to loosen amid political reform and economic strain. In 1989, facing mass protests, East German officials open travel between East and West Germany. Almost immediately, citizens on both sides begin tearing down the Berlin Wall. Reactions are muted among NATO countries. Britain and France, fearing instability as well as a resurgent German power, prefer that Germany remain divided. But President George H.W. Bush and other U.S. officials support German reunification. Bush works with German and Soviet leaders to help build wider support. In 1990, both German states—alongside the United States, Britain, France, and the Soviet Union—sign an agreement paving the way for reunification.

Amid increasing economic strain in the 1980s, Soviet leader Mikhail Gorbachev begins a series of economic and political reforms. Yet as those reforms struggle to halt the bloc’s economic decline, some Soviet republics begin advocating for greater sovereignty within the Soviet system. Eventually, calls for full independence follow in many of the union’s fifteen republics. Throughout that time, Bush continues to work with Soviet leadership, encouraging reforms while making sure such rapid changes don’t lead to widespread instability. At the end of 1991, after a failed coup in Russia erases the Communist Party’s remaining credibility, the Soviet Union fully dissolves. The Cold War is over. But new challenges soon arise. In the immediate aftermath, U.S. economic advisors try to help the new Russian Federation transition to capitalism. The rapid economic transition proves devastating for ordinary Russians, however, producing hyperinflation, widespread poverty, and a perception that Western advisors had served elite interests at the public’s expense.

The United States emerges from the Cold War as a dominant global power. But new challenges soon emerge. Terrorism, climate change, regional instability, and China’s rise to superpower status spur renewed debate over the United States’ global role.

For decades, U.S. policy toward the Middle East has sought to maintain regional stability, protect Israel, and ensure favorable access to the region’s oil. In 1990, Iraq invades Kuwait, threatening many of those interests. Iraqi dictator Saddam Hussein believes he can take over Kuwait without U.S. interference. But Hussein miscalculates. Bush secures UN authorization to act against Hussein. Bush, arguing that the situation in Kuwait represents a defining moment of the post–Cold War era, also secures congressional authorization for an intervention. The United States leads an international coalition against Iraq, driving its forces from Kuwait within six weeks. For U.S. leaders, the outcome marks a victory for a new international order characterized by post–Cold War international cooperation around shared rules and values. It also demonstrates the technological might of the U.S. military. For Americans, the war helps restore a confidence in the country’s military that had remained shaken after Vietnam.

In the early 1990s, the United States and Canada implement a free trade agreement. Meanwhile, Mexico begins to relax long-standing protectionist policies and open more of its economy to world trade. But Mexico still faces U.S. tariffs and quotas on its exports. It proposes negotiating a trade agreement to reduce those barriers. Hoping to improve relations and open Mexico’s market to American goods, the United States agrees. Canada asks to join the negotiations, fearing that a bilateral U.S.-Mexico trade deal will undermine the U.S.-Canada deal. The three countries negotiate the North American Free Trade Agreement (NAFTA), which over time eliminates most tariffs between each and creates one of the world’s largest trading blocs. U.S. consumers enjoy lower costs and wider choices, but at a cost. Many U.S. firms either close or move jobs south of the border to take advantage of Mexico’s lower wage rates and less onerous regulations. The resulting job losses create lasting political resentment. Though controversial, NAFTA further integrates North America’s economies and serves as a model for future U.S. free trade agreements.

On September 11, 2001, members of the terrorist group al-Qaeda hijack four commercial planes and fly two into the World Trade Center in New York and one into the Pentagon in Washington. The fourth crashes in a field in Pennsylvania after passengers try to retake control of the plane from the hijackers. The attack kills 2,977 people, representing the largest terrorist act in history and one of the deadliest days in U.S. history. Counterterrorism, a growing concern throughout the 1990s, now becomes a top foreign policy priority. The immediate focus of the U.S. response is Afghanistan, where the United States leads a coalition force that unseats a ruling Taliban government that was harboring al-Qaeda leaders. Osama bin Laden, the leader of al-Qaeda, escapes, as do most other senior al-Qaeda members. (In 2011, U.S. special forces will kill bin Laden in Pakistan.) The U.S.-backed government in Kabul, Afghanistan, struggles to contain a growing Taliban-led insurgency. Afghanistan, however, isn’t the only site of the new war on terrorism. The United States steps up counterterrorism operations globally, in regions ranging from Latin America to sub-Saharan Africa, building new security partnerships and deploying military and intelligence resources to locations not previously central to U.S. defense strategy.

Starting in the 1980s, China’s economy grows rapidly as it expands manufacturing and trade with the world. The United States signals its support for China to join the World Trade Organization (WTO), an international body that sets international trade rules. The WTO requires members to reduce tariffs, protect intellectual property rights, open markets, and submit to dispute resolution. The United States believes that including China will accomplish several goals: open the Chinese market to U.S. goods, make China change its trading practices, and even push China toward democratic reforms. Though U.S.-China trade increases, those other goals fail to materialize. Instead, China will use WTO membership to its advantage, and its Communist Party government will remain in power. By 2017, U.S. leaders across both parties will conclude that engagement through trade has failed to transform China, shifting to a strategy of strategic competition with China as a great power rival. The optimism surrounding China’s WTO accession will give way to a fundamental reassessment of the U.S.-China relationship.

In the wake of the 9/11 attacks, a new national security strategy takes shape: preemption. The United States will not wait for terrorists or rogue states to attack; it will now seek out and prevent threats before they fully materialize. President Geroge W. Bush and his advisors argue that Iraq is building weapons of mass destruction. Some officials also claim Iraq helped al-Qaeda carry out the 9/11 attacks. The UN Security Council agrees to U.S. demands for tougher weapons inspections in Iraq but refuses to authorize using military force to unseat Iraq’s government. Rebuffed at the United Nations, the United States forms a “coalition of the willing” that invades Iraq. The coalition force defeats Iraq’s military and removes its longtime dictator, Hussein. But inspectors find no weapons of mass destruction. Over the following years, Iraq spirals into insurgency and civil war. Meanwhile, U.S. public support for the war plummets. By the time the United States withdraws in 2011, more than 4,400 U.S. soldiers and more than 100,000 Iraqis have been killed. The United States has little to show for its massive expenditure of blood and money in Iraq.

In the twenty-first century, global attention increasingly turns to transnational threats, including climate change. In December 2015, representatives from 196 nations gather in Paris to negotiate a landmark international climate agreement. Prior climate agreements required industrialized countries to slash their emissions of heat-trapping gases. But the Paris Agreement commits all countries to take steps to limit global temperature increases to 2°C above preindustrial levels—and ideally, no more than 1.5°C. The agreement enters into force in November 2016 after enough countries ratify the treaty. In the United States, President Barack Obama strongly supports U.S. participation, arguing that climate change is a critical national security and economic challenge. But President Donald Trump will announce U.S. withdrawal in 2017, arguing that complying with the agreement’s terms would hurt the U.S. economy. President Joe Biden will then rejoin the agreement in 2021, only for Trump to once again withdraw in 2025. The Paris Agreement represents an unprecedented global commitment on climate change, and as of early 2026, the United States will remain the only country to have left the agreement.

In his first term as president, Trump revises U.S. trade policy with China. The United States has grown frustrated with Chinese trading practices, which U.S. officials say violate WTO rules. Officials believe China has gained an unfair advantage through its protectionist policies, threatening—among other American interests—U.S. jobs, manufacturing, and technologies. As a result, the United States increases tariffs on China, taxing nearly half of all Chinese imports. Those tariffs kick off a trade war. China responds with tariffs on nearly 70 percent of U.S. imports. Tension between the two countries—the world’s largest economies—begins to reshape global trade, as companies and countries rethink their economic reliance on the United States and China.

After almost two decades of war, the United States withdraws from Afghanistan. The conflict has been long and costly. More than six thousand coalition forces and contractors have been killed, as well as more than one hundred fifty thousand Afghan soldiers and civilians. Meanwhile, the United States has spent over $2 trillion in a war that has accomplished little. A resurgent Taliban continues to attack Afghan forces and civilians, despite a peace deal with the United States. As U.S. forces leave, the Taliban sweeps across the country, retaking the capital. Alongside failures in Iraq, the U.S. War in Afghanistan represents another military defeat, one that will leave Americans divided over their country’s role in the world.