Prof. John Mearsheimer: 250 Years of American Foreign Policy

ELI5/TLDR

The United States has spent 250 years doing one thing extremely well: becoming the only country in its neighborhood so powerful that nobody else can tell it what to do. It achieved this through relentless territorial expansion, strategic patience in two world wars (letting others pay the “blood price” before swooping in late), and a Monroe Doctrine that amounts to “this hemisphere is ours, deal with it.” Now the same playbook is aimed at China, which sensibly wants to be the America of East Asia — and America sensibly won’t let it.

The Full Story

The Declaration: Two Ideas That Don’t Really Get Along

Mearsheimer reads the Declaration of Independence as two documents stitched together. One is liberal and universalist — all men are created equal, natural rights, the whole Enlightenment package. The other is nationalist and particularist — we’re breaking away from Britain to form our state, for our people. Liberalism says everyone on the planet has the same rights. Nationalism says our nation comes first.

He spent three hours debating this tension one-on-one with Viktor Orban. Orban’s position: liberalism is acid that dissolves the roots of a nation state. Mearsheimer’s position: America managed to hold both together. Neither convinced the other.

Manifest Destiny Was Not Just East-to-West

The expansionist impulse predates the republic. Colonists wanted to push westward; Britain said no because westward expansion meant expensive wars with Native Americans and the French. This disagreement was one of the causes of the revolution itself.

Once independent, America didn’t stop at the Pacific. It tried to conquer Canada in 1812 (the reason Ottawa is the capital instead of Toronto — the Canadians expected a return visit). The entire Caribbean would have been absorbed if not for the slavery question — bringing sugar-producing islands in meant more slave states, and northerners blocked it. Manifest destiny went in every direction. The Pacific Ocean was the only thing that stopped it.

“If the Pacific Ocean had been land, we would have just kept going.”

Regional Hegemony: The Only Club With One Member

A regional hegemon is a country so dominant in its part of the world that no neighbor can challenge it, and no outside great power is allowed in. There has only ever been one: the United States.

No country can be a global hegemon — the planet is too big and there’s too much water. So the next best thing is regional dominance. America achieved it through manifest destiny, mass immigration from Europe, industrialization, and the Civil War (which welded a loose confederation into a single powerful state). Had the South won, there would have been two great powers in the Western Hemisphere and no hegemony.

The British wanted the South to win for exactly this reason. It was, Mearsheimer notes, a fundamental mistake — because the resulting American colossus later rescued Britain twice.

The Monroe Doctrine is the enforcement mechanism: no country in the hemisphere may ally with a distant great power or invite foreign military forces in. When the Soviets tested this in Cuba, JFK made it categorically clear.

“How many of you go to bed at night worrying about anybody in this hemisphere attacking us? The answer is nobody. And on our eastern border and our western border, we have fish.”

The Blood Price: Why America Shows Up Late to Wars

America’s strategy in both world wars was the same: let other countries do the dying, and intervene only when the “bad guys” look like they might actually win.

In World War II, the Soviets lost 27 million people. America didn’t land at Normandy until June 6, 1944 — eleven months before the war ended. At that point, 93% of German casualties had been inflicted on the Eastern Front. The Soviets won World War II. America tipped both world wars at the end, which is the ideal outcome if you’re the one doing the tipping.

The reason Hitler was so hard to stop early on: everybody was buck-passing. Britain wanted France to fight. France wanted the Soviets to fight. The Soviets wanted Britain and France to fight. America wanted all of them to fight. This let Hitler pick off opponents one by one.

“Our basic policy when you’re dealing with a rival great power is to let the locals, the neighbors defeat that great power. And if we do have to come in, come in at the last moment and win the victory.”

American Exceptionalism: The Realist’s Uncomfortable Version

Most Americans define exceptionalism as nobility — city on a hill, moral beacon, etc. Mearsheimer finds this difficult to square with the record. He cites a Lancet study (November 2025) estimating that American sanctions between 1971 and 2021 contributed to 38 million deaths. Add the Iraq war, the economic strangulation of Venezuela, Cuba, and Iran, and the ledger gets heavy.

His personal resolution: he loves living in liberal America, thanks his stars for it, but doesn’t confuse domestic virtue with foreign policy virtue.

“The United States is an incredibly ruthless great power. We don’t teach that in school, but that’s the way the world works. We gussy it up with all this liberal ideology about how noble we are.”

The Cold War and the Ideology Question

Mearsheimer sees security competition as always trumping ideology. World War I was pure security — no ideological dimension. World War II mixed fascism, communism, and liberalism into a three-way ideological clash layered on top of security competition. The Cold War was both, but survival concerns drove the key decisions. Even Hitler, he argues, was ultimately driven by strategic rather than ideological logic — though the ideology was real and heinous.

Three Visions of the Post-Cold War World

Three scholars at Chicago made three predictions as the Cold War ended:

Fukuyama (1989) — End of History. Liberalism won. Every state would become a democratic market economy. The biggest future problem would be boredom. This looked brilliant through the 1990s.
Huntington (1993) — Clash of Civilizations. The world organizes around civilizations, not nation states. Islam and China vs. the West. This looked prescient after 9/11.
Mearsheimer (1990/2001) — Tragedy of Great Power Politics. Great power competition never ends. When unipolarity fades, balance-of-power politics returns. This looked irrelevant for two decades.

From roughly 2017 onward, with China as a genuine great power and Russia revived, multipolarity returned. Mearsheimer’s framework became the one hedge fund managers call about, which he finds both vindicating and concerning.

China: The Big One

China wants to be the regional hegemon of East Asia — exactly what America did in the Western Hemisphere. Mearsheimer says if he were Xi Jinping’s national security adviser, he’d recommend the same thing. But America will not permit a peer hegemon anywhere, so the US-China competition will be the defining conflict of this century.

The military dimension is manageable for now — the US and allies (Japan, Australia, Philippines, South Korea, Taiwan) can deter China from taking Taiwan or dominating the South and East China Seas. The economic and technological dimension (AI, quantum computing) is where the race is tightest. China’s manufacturing base is formidable, and Mearsheimer isn’t sure the US can win the tech race decisively — perhaps the best case is staying abreast.

The Overstretch Problem

The Q&A surfaces a recurring theme: America is stretched across too many theaters simultaneously. The Western Hemisphere (Venezuela, Cuba, Greenland, Canada), Iran and the Middle East, Ukraine, and East Asia all demand attention and weapons. General Kaine reportedly warned Trump that US weapons inventories can’t sustain a prolonged Iran conflict — 4,000 Tomahawk missiles sounds like a lot until you realize you can burn through them in two weeks.

On Ukraine, Mearsheimer is blunt: Ukraine is in a “demographic death spiral,” the war is lost, and encouraging Ukrainians to keep fighting is “morally reprehensible.” He attributes the war entirely to NATO expansion — specifically the 2008 Bucharest declaration that Ukraine would join NATO, which Russia treated as an existential threat.

On Russia’s broader ambitions, he dismisses the idea that Putin wants to recreate the Soviet empire. Occupying hostile nationalist populations is a nightmare (the Soviets learned this managing Eastern Europe), and the Russian military can barely handle eastern Ukraine. Invading western Ukraine would be “trying to swallow a porcupine.”

Claude’s Take

claude_score: 8 — This is a masterclass in realist grand strategy from its most prominent living advocate. Mearsheimer is doing what he does best: taking 250 years of American foreign policy and running it through a single clean theoretical lens (offensive realism), and making it feel inevitable rather than chosen.

What’s genuinely strong: the buck-passing analysis of WWII entry timing, the regional hegemony framework, and the point about the Declaration containing two contradictory ideologies. These are not controversial among IR scholars — they’re close to consensus positions stated with unusual clarity. The 93%-of-German-casualties-on-the-Eastern-Front statistic is well documented and still shocks audiences raised on Saving Private Ryan.

What’s weaker: the monocausal explanation of the Ukraine war (NATO expansion alone) is where Mearsheimer is most contested by fellow scholars. He dismisses any Russian imperial ambition, which requires ignoring some of Putin’s own statements about Ukrainian nationhood being illegitimate. The 38 million deaths from sanctions figure (attributed to Lancet) deserves scrutiny — sanctions studies vary wildly in methodology and that number seems to aggregate indirect mortality estimates that are debated. He presents it as settled fact.

The blind spot is the same one that’s followed Mearsheimer for decades: realism explains why great powers compete but struggles with how they choose among options. His framework predicted US-China tension (correct) but didn’t predict the specific form it would take. And his insistence that ideology is always subordinate to security leads him to underweight cases where leaders genuinely act on ideological conviction to their own strategic detriment.

Still, as a 30-minute sweep through 250 years of US foreign policy aimed at a general audience, this is about as good as it gets. The man has been giving variations of this talk for decades, and it shows — in a good way. The arguments are load-tested. The delivery is conversational. If you’re new to realist IR theory, this is an excellent entry point. If you already know Mearsheimer, there’s nothing new here, but the Iran and Ukraine Q&A material reflects genuinely current analysis.