While Washington’s war with Iran drags on, month after month, without any end in sight, the world is witnessing the very real limits of US global power. As President Donald Trump lurches repeatedly from threats of devastation to promises of peace, it’s becoming increasingly clear that US military might is no longer capable of subduing even a mid-sized power like Iran, much less holding the rest of the world in its thrall.

Amid all the drama of air raids, drone strikes, and naval blockades, there are deeper geopolitical forces at play that lend a lasting historical import to events in the Persian Gulf—dynamics best seen by comparing two newspaper editorials with revealing similarities despite the 80 years separating their publication.

Writing in 1942, during some of Britain’s darkest days in World War II, the editors of the venerable London Times looked far beyond the relentless German attacks on their forces in Egypt or the Nazi U-Boat sinkings of Royal Navy ships in the Atlantic to predict their empire’s future with an uncommon prescience. With its contradictory motto of “Imperium et Libertas” (Empire and Liberty), the vast British Empire, which still covered a quarter of the globe, had already become what those editors called “a self-liquidating concern.” Once the “temporary circumstances” that had allowed Britain’s ascent—naval dominance, industrial preeminence, and “the relative weakness of rival states”—faded, that empire’s “ultimate reliance on coercion” could no longer hold. Ready for self-governance, Britain’s many colonies, the editors suggested, would soon begin breaking away and so eclipse the empire. And that prediction couldn’t have been more accurate. Within five years of that editorial’s publication, the British Empire had already started to break apart.

Writing in a May 2026 edition of The New York Times, contributing editor Christopher Caldwell made a strikingly similar prediction about the future of US global hegemony. Under the provocative headline “America Is Officially an Empire in Decline,” Caldwell noted some unsettling parallels between the fate of America today and Great Britain 80 years ago. Back then, England was “deindustrializing, overcommitted, complacent,” and found itself “essentially bankrupt” by the end of World War II. Apart from its “ill-fated attempt” to seize the Suez Canal from Egypt in 1956, however, it managed to decolonize in a successful fashion by giving up “territories it could no longer afford.” As he points out, Britain even “wound up on reasonably good terms with its former colonial possessions.”

Probe deeper still for the causes of the ongoing all-American imperial decline and you’ll come to the most fundamental but generally least noted factor in the rise and fall of every world empire for the past 500 years: energy innovation.

At the start of his second term as president in 2025, Donald Trump, Caldwell continued, “had a chance of pulling off something similar” by withdrawing “to a less expansive sphere of influence” and “refocusing American attention on the Western Hemisphere.” Caldwell considered that strategy potentially “workable” since “imperial systems, whatever you call them, last only as long as their means are adequate to their ends.” Instead of keeping to that plan, however, Trump “has overextended the empire dangerously” by his intervention in Iran, which has now become nothing less than a “watershed in the decline of the American empire.”

To test the probability of Caldwell’s prediction coming true, we need to go beyond the immediacy of the Iran crisis to explore both the deeper causes of US global decline and its likely long-term consequences for both the United States and the rest of the world.

Explaining US Imperial Decline

Since most Americans came late (if at all) to the realization that their country was indeed an imperial power, and a stunningly powerful one at that, they have generally remained oblivious to its aging and the inevitable erosion of global power that accompanies such aging. Ever since, in the late 18th century, English scholar Edward Gibbon published his monumental, multi-volume study, The Decline and Fall of the Roman Empire, succeeding imperial rulers have tended to assume that their imperial realms would last, like ancient Rome’s, half a millennium or more. Adolf Hitler, with his dream of “the Thousand-Year Reich,” was hardly the only one to share such an illusion.

But the modern age, with its rapid economic and technological change, has only accelerated imperial decline. Britain’s sprawling global empire lasted just 90 years (1857-1947) and France’s African empire, covering a quarter of that continent, was about the same, while the Soviet empire in Eastern Europe barely lasted 40 years (1945-1989). So, for the US global imperium to have survived for 80 years (1945-2026) should be considered the most anyone could realistically expect for a modern empire.

Since the US-led global order—exemplified by the International Monetary Fund (IMF), the World Bank, and the World Trade Organization (WTO)—had indeed presided over 80 years of sustained global economic growth, there is a distinctly American twist to the British concept of the “self-liquidating concern.” As the rest of the world enjoyed a rapid economic recovery from the ravages of World War II, America’s share of the global economy declined from an overwhelmingly dominant 50% in 1945 to less than half that figure today. Using an index called PPP (Purchasing Power Parity) that measures the real value of economic growth, the IMF calculates that, in 2026, China is producing 20% of global economic output, the US just 15%, and the European Union (EU) 14%.

But the relative economic decline of the United States should by no means be the crucial measure of its failure. Quite the opposite, in fact. It should be considered a tribute to Washington’s success in leading the world economy to unprecedented prosperity. In those 80 years since the end of World War II, the US economy has grown fast, but many other nations have grown faster still. An economic giant that could structure the global economy as it wished in 1945, the US must now negotiate the terms of trade with a host of peer rivals—whether economic powers like China; major players like India and Japan; or a growing number of regional blocs like the European Union, South America’s Mercosur, and Asia’s ASEAN.

Probe deeper for the forces now driving America’s decline and you’ll notice an underlying geopolitical dimension. As I explained in my new book, Cold War on Five Continents, the US achieved its global hegemony after World War II by maintaining an unwavering geostrategic dominance over the Eurasian land mass. Through its military alliances at both axial ends of that vast continent—the multilateral North Atlantic Treaty Organization (NATO) in the West and five bilateral defense pacts with countries ranging from Japan to Australia in the east—the US imposed an “Iron Curtain” of 5,000 miles of anti-communist containment across Eurasia. Using those axial ends as anchors, the US encircled the continent with three naval armadas, hundreds of military bases, and thousands of jet aircraft. With Moscow geopolitically isolated and Beijing still a developing power, Washington could simply sit back and wait for the Soviet Union’s increasingly stagnant socialist economy to collapse and its dozens of restive satellite states to break free—as they all did between 1989 and 1991.

In the 35 years since that great Cold War victory, Washington’s foreign policy elites have pursued policies that might all too accurately be branded “bipartisan mismanagement” of the US geopolitical position in Eurasia. As home to 70% of the world’s population and an even greater share of its productivity, that continent remains the epicenter of global power (as it has been for the past 500 years). No nation can contend for world leadership without competing for geopolitical influence there.

From 2001 to 2021, both Democratic and Republican administrations oversaw long-term military occupations of Afghanistan and Iraq that cost thousands of American lives, millions of civilian deaths, and trillions of dollars in treasure. While Washington was wasting an estimated $5.8 trillion on those pointless, profitless wars, China’s foreign currency reserves surged from just $200 billion in 2001 to a massive $4 trillion by 2014. Drawing on such unprecedented reserves, President Xi Jinping launched his trillion-dollar Belt and Road Initiative that quickly laid down a grid of railroads, roads, pipelines, and ports across Eurasia from the Baltic to the South China Sea. By the time American troops finished their humiliating retreat from Afghanistan in August 2021, China had become the dominant power in Central Asia and the US position in Eurasia was starting to crumble.

In his second term, President Trump’s foreign policy has further weakened the US global position. At the western axial end of the Eurasian continent, he compromised NATO, the largest and longest-lasting alliance in modern military history, by pressing Denmark, a founding member of the alliance, to cede its sovereign territory of Greenland, creating a serious crisis and compelling the Europeans to begin acting autonomously when it came to both trade and defense issues.

At the eastern end of Eurasia, Trump’s intervention in Iran and the blocking of key oil supplies to Asia, thanks to the closing of the Strait of Hormuz, weakened longstanding bilateral alliances with Australia, Japan, the Philippines, and South Korea. The thousands of missiles the US has fired at Iran have also reduced its ability to defend the island of Taiwan and forced Washington to begin withdrawing stocks of missiles from South Korea—exposing both the limits of its military power and Asia’s lowered priority.

As The New York Times editorial board put it after Donald Trump’s recent Beijing summit with Chinese leader Xi Jinping (where the US president showed a “worrisome lack of interest” in Taiwan), “America’s inability to defeat Iran’s much smaller military has raised questions about........

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