US President Donald Trump speaks about the conflict in Iran in the James S. Brady Press Briefing Room of the White House on April 6, 2026, in Washington, DC. (Photo by AFP)By Brahma ChellaneyThe Japan TimesIn barely 15 months, U.S. President Donald Trump has generated more global upheaval than most leaders do in a lifetime.By eroding international norms, unleashing cascading crises and roiling world markets, he has emerged as a principal driver of global instability. And he still has 33 months left.There is no modern precedent for what is now unfolding. A single leader — at the helm of the superpower that built and sustained the post-World War II international order — is dismantling it at speed, while openly mocking the very rules that once underpinned American power.Since returning to the White House, Trump has cast aside longstanding legal norms, authorized military strikes across multiple sovereign states and weaponized economic interdependence against allies and adversaries alike. From the slow strangulation of Cuba through blockade-induced deprivation to a war on Iran that has triggered worldwide turmoil, his actions have pushed the international system into uncharted territory.Trump launched his war on Iran, as he did his military intervention in Venezuela weeks earlier, in the language of dominance. But its consequences unfolded globally in the language of scarcity — of fuel, food and even survival.Iran and Venezuela account for almost one-third of global proven oil reserves. Bringing both into Washington’s strategic orbit would give the U.S. an unprecedented lever over global energy markets — one that could be used not merely to influence prices and supply, but to discipline rivals and steer the economic and foreign-policy trajectories of partners.Trump’s vision of America’s global “energy dominance” was on display again at his April 6 news conference, where he pointed to Venezuela as a model for dealing with Iran, citing his seizure of Venezuelan oil. Describing himself as a businessman, Trump said he wants to likewise take Iran’s energy resources once the conflict is over. “To the victor belong the spoils,” he declared.It was a revealing admission: Control over Iran’s vast energy wealth lies at the heart of his war of aggression.What began on Feb. 28 as a joint U.S.-Israeli assault on Iran, however, quickly metastasized into the most consequential energy shock in modern history. Unlike the oil crises of 1973 and 1979, driven largely by political embargoes, the current upheaval stems from the physical destruction of energy infrastructure and the breakdown of critical supply routes.Because energy underpins the global economy, the shock could not be contained. It rippled outward — destabilizing food systems, straining financial markets and hitting the poorest countries the hardest.In terms of global impact, the Ukraine conflict pales by comparison. What began as a regional war with global implications evolved into a globe-spanning crisis driven by a single regional conflict. That is the enduring lesson of the Iran war.More fundamentally, Trump’s neoimperial impulse is no longer latent; it is hardening into an expansionist doctrine that echoes the playbook of colonial empires rather than the norms of the post-1945 order. His push to increase already massive U.S. defense spending by over 50%, to $1.5 trillion, underscores the scale of that ambition.From renewed pressure for U.S. control over Greenland and the Panama Canal to open-ended military interventions in Venezuela and Iran — and even talk of redrawing borders or relocating populations — Trump has revived a logic more familiar to the age of empires. The Monroe Doctrine, once regional, has effectively been globalized.The question is no longer whether Trump is disrupting the international order. It is whether there is any historical parallel for such systematic disruption from within. There is not.The U.S. was the principal architect of the current system. The rules governing trade, sovereignty and collective security were largely American designs, forged after World War II to prevent precisely the kind of instability now unfolding.What makes this moment unique is not simply that these rules are being broken, but that they are being dismantled by an American president.History offers examples of destructive leaders — such as Mao Zedong, Pol Pot, Idi Amin and Moammar Gadhafi — but they operated on the margins of the international system or in opposition to it. Trump is different. He is tearing down the house from inside.Nowhere is this more evident than in his weaponization of interdependence. Trade, once treated as a stabilizing force, has been recast as an instrument of coercion. Tariffs are no longer just economic tools; they are strategic weapons.By linking military protection to trade concessions and tribute-like payments, Trump has transformed alliances into transactional arrangements — security for sale. The postwar idea of collective defense is giving way to something closer to protection racketeering.This shift signals a profound reordering of international relationships, in which commitments are perpetually subject to renegotiation.Equally consequential is the erosion of sovereignty. U.S. military strikes have extended across the Middle East, Africa and even into the Caribbean, targeting states without clear legal justification under the U.N. Charter.Earlier eras did see U.S. expansionist doctrines — from Theodore Roosevelt’s “Big Stick” diplomacy to William McKinley’s imperial ventures. But those belonged to a pre-1945 world, before the current international norms took shape. Today’s actions carry greater weight precisely because they defy a system the U.S. itself helped build.The war on Iran marked a particularly dangerous gamble. Trump is the first leader to trigger a global energy crisis through direct military action of his own making.At the same time, his administration is hollowing out multilateralism — the connective tissue of the international system. Just weeks before launching the Iran war, the U.S. withdrew from 66 international organizations in a single stroke, including the World Health Organization, while sanctioning International Criminal Court officials.Other leaders have challenged international norms, including Saddam Hussein and Vladimir Putin, but as outsiders. Trump’s approach is more destabilizing because it represents an insider threat. By abandoning agreements like the Paris climate accord, while openly entertaining territorial ambitions from Greenland and Canada to the Panama Canal, his administration has signaled that it no longer considers itself bound by the rules Washington once championed.If the international system’s principal guarantor no longer believes in it, what remains?To find even a loose historical analogy, one must look further back. Napoleon reshaped Europe through force; Bismarck discarded alliances in pursuit of advantage. Yet neither operated within a global order they themselves had constructed and sustained. What we are witnessing is something unprecedented: a great power dismantling its own architecture of order.The consequences are already visible. Alliances are fragmenting. Markets are volatile. Smaller states are hedging, recalibrating or simply absorbing the shocks. The world is moving beyond Pax Americana — but not toward a stable alternative. Instead, it is drifting into uncertainty.Today, the greatest threat to international peace and security is not a rising challenger. It is the transformation of the international system’s central pillar — the U.S. — into its principal destabilizer.From rising fuel and food prices in Africa to fiscal stress across Asia and Latin America, the costs of Trump’s ambitions are being borne far from the corridors of power where they were conceived.Brahma Chellaney, a longtime contributor to The Japan Times, is the author of nine books, including “Water: Asia’s New Battleground.”