When the Iran war began in late February, China looked vulnerable.

The world’s largest crude oil importer, China has in recent years depended on imports for more than 70 percent of its consumption, with around half coming from the Middle East. The throttling of the Strait of Hormuz, months ­­after the United States had disrupted global oil flows from Venezuela, seemed to present Chinese leaders with one of their greatest strategic fears: a crippling oil shock they could not control.

Instead, President Trump’s war on Iran has been a welcome revelation for China, which absorbed one of the most severe oil-supply disruptions of the modern era, demonstrating that years of preparation had mitigated a huge vulnerability and potential source of U.S. leverage over Beijing in a geopolitical confrontation.

China was self-sufficient in oil until 1993, when the escalating needs of its booming economy turned it into a net importer. Oil imports soared in the years that followed, prompting President Hu Jintao to warn in 2003 that hostile powers could seek to control the Malacca Strait, the sea lane in Southeast Asia through which much of the country’s imported oil travels.

Beijing responded with a wide-ranging strategy to reduce that exposure. It diversified supply sources to limit the share of oil coming from the Middle East and began to build up what are now estimated to be the world’s largest crude oil stockpiles, roughly equal to those of the United States and Japan combined. China has pushed aggressively to shift passenger cars from fossil fuels to electric power, making it by far the world’s largest market for electric vehicles today, and it is extending that effort to trucks. Electricity generation relies almost entirely on domestic energy sources such as coal, nuclear, hydro and, increasingly, wind and solar.

That long-term strategy has been put through a real-world stress test by the Iran war — and, so far, it has passed.

The Hormuz disruptions drove oil prices up. But unlike during a 2021 Chinese coal shortage, when the government instructed importers to urgently secure energy supplies, it didn’t hit the panic button this time. Inflows of oil to China plunged as importers slashed purchases. The country fell back on its stockpiles while restricting exports of transport fuels to keep more at home. Higher fuel prices also appear to have pushed many Chinese drivers to use public transportation, taxis or ride-hailing services, much of which run on electricity.

As a result, while some governments in Asia were forced to take painful emergency measures such as rationing fuel, raising prices and reducing public services, China’s economy was not materially disrupted. Its purchasing restraint in global oil markets also eased pressure on prices, sparing the world an even bigger oil shock and, ironically, softening the domestic political fallout for Mr. Trump by limiting the pain at the U.S. pump.

China’s ability to weather the Iran war’s oil disruptions came as a surprise to many. It shouldn’t have — this is exactly what the government has spent years preparing for.

Chinese leaders see energy as a source of national and geopolitical power on par with industrial, technological and military strength. In 2021 they called for China to become an “energy powerhouse” — less reliant on fossil fuels yet still able to provide abundant and reliable power to the economy. Even before the war began in February, Communist Party-controlled media said achieving that goal was critical for China in “gaining the initiative in great-power competition” — an unmistakable reference to the contest with the United States in power-hungry industries like advanced manufacturing, data centers and artificial intelligence.

China’s latest energy plan, adopted this year, reflects that ambition. It calls for developing more renewable energy, as well as nuclear and hydropower, while retaining coal — long the backbone of China’s power system — as a critical backstop. The country is also investing heavily in new transmission lines to move power from resource-rich regions to the cities and factories that need it, in batteries and other storage capabilities, as well as in grid upgrades to keep electricity supplies steady.

The United States has great energy advantages of its own. It remains the world’s unrivaled oil and gas power, with abundant domestic supplies, the capacity to process and export them at enormous scale and large strategic reserves. But its electricity system is struggling to keep pace with rapidly rising demand from a new wave of power-gobbling industries.

For decades, oil leverage seemed to rest with countries that controlled supply — OPEC, Russia and other major exporters, as well as U.S. shale producers — and could move prices by tightening or loosening the taps. The Hormuz crisis has shown that China is becoming a new type of energy power: an oil importer so large that it is able to influence global oil prices and withstand external disruptions.

China’s dependence on imported oil remains substantial, but the geopolitics of energy are shifting from control of oil flows to control of electrified industrial systems. China has a clear head start in that transition, one that strengthens its hand in the industrial and strategic competition with the United States.