Many Americans watched with surprise as Silicon Valley’s most powerful entrepreneurs fell in behind Donald Trump when he returned to the White House last year. The same C.E.O.s and investors who once celebrated globalization and consumer apps were suddenly embracing patriotism and advanced weaponry such as killer drones.

Don’t misconstrue this as a thoughtful political shift, or a change of heart. Silicon Valley has always been fertile ground for mythmaking, and no myth is bigger than the notion that the ideological chasm between the Valley and the Pentagon is too vast to bridge.

For tech companies, the personality and politics of the person occupying the White House is less important than that person’s willingness to buy what Silicon Valley is offering. The federal government is, at base, a purchasing agent, and Silicon Valley’s pivot to the military — and to Mr. Trump — is less a story of political conversion than of market adaptation.

Silicon Valley’s values haven’t changed, just its customers.

People seem to forget that Silicon Valley was largely born on the back of Pentagon funding during the Cold War. Fairchild Semiconductor, a company that became the wellspring of the computer chip industry’s growth, was one of those beneficiaries. Conventional wisdom held that, by 2016, many firms, not to mention their employees, found the idea of working on defense projects distasteful, if not unthinkable. Mr. Trump’s election that year seemed to widen the divide. In 2018, Google, under pressure from employees, pulled out of Project Maven, a Pentagon-funded A.I. project to advance drone warfare.

The real dividing line between the tech industry’s bosses and the Pentagon had little to do with politics and a lot to do with markets. For more than three decades, tech industry leaders such as Apple and HP were focused on consumers, whether personal computers, smartphones or later, apps. That market is global, which in the 2000s led these companies to start selling their wares in China — where many of the firms were already basing their manufacturing — which offered access to more than one billion consumers.

Unlike today, China in the early 21st century represented more opportunity than threat, which led venture firms such as Sequoia Capital to make enormous investments there. Digital service companies, such as Uber, Airbnb and Facebook, chased the market. Investors marveled at China’s burgeoning tech economy, even as Washington was beginning to warn about the strategic threat from Beijing. “China should be another United States from an economic standpoint,” Marc Andreessen, a prophet of the venture capital world, said in 2013, the year China’s Communist Party leader, Xi Jinping, became president. “Beijing should be another Silicon Valley.”

China has since closed its doors to many American technology companies. Relations between Washington and Beijing deteriorated over the next decade. Recently, the Tesla C.E.O., Elon Musk, denied reports that he is considering jettisoning his China business to enable the merger of his electric vehicle company with SpaceX, a major Pentagon contractor. But he’s well aware of the difficulties his business there presents.

Today, the shift from consumer markets to defense industries is clearly visible at Mr. Andreessen’s firm, which has a dedicated division, called American Dynamism, that focuses on investing in weapons and technologies aimed at competing with China. Or even, potentially, waging war with China. Sequoia, one of Silicon Valley’s most storied venture capital firms, has spun out its China business and joined the growing number of venture capital firms funding companies dedicated to building military weapons. Sequoia’s initial defense tech investment was in a start-up founded by a 19-year-old that is building killer drones.

As for Google, it only took a few years for the company whose motto was once, “Don’t be evil,” to again pursue contracts with the Pentagon. Not because of patriotism, but apparently out of financial self-interest. The federal government, and particularly the Pentagon, has emerged as one of the world’s largest customers for A.I. and autonomous weapons — technologies needed for war in the future, especially the Pacific. Earlier this year, Google agreed to provide the Department of Defense with A.I. for classified networks after Anthropic became embroiled in a dispute with the Pentagon over how its A.I. models were being used.

For Anthropic, the issue was never a choice between working for the Pentagon or competing with China, but a question of how much control it would have over its models and their use. Anthropic’s C.E.O. has frequently warned about the threat from Beijing, even saying that selling A.I. chips to China is like “selling nuclear weapons to North Korea.”

That’s quite the pivot. “Silicon Valley has changed partly because people realized you’re not going to make any money in China,” noted the Palantir Technologies C.E.O., Alex Karp, in 2024, as tech were again chasing defense business. Peter Thiel, the right-wing tech billionaire who co-founded Palantir with Mr. Karp more than 20 years ago, was early to recognize the potential and was long skeptical of China. (Not surprisingly, Mr. Thiel was also the first major Valley figure to back Mr. Trump in 2016, though he later soured on the Republican president.)

Few things illustrate this dynamic better than the poster child for defense start-ups, Palmer Luckey, the Hawaiian shirt-clad founder of Anduril Industries, which makes A.I.-powered weapons. Mr. Luckey was just 19 when he co-founded Oculus Rift to build virtual reality headsets for consumers. The Oculus Rift development kit from 2013 ended with a single line: “Made in China.” But like other tech companies, Oculus grew disillusioned with China as a consumer market, even if it still needed it as a manufacturer. The following year, Oculus suspended sales to China, reportedly over aggressive scalpers who were reselling the company’s hardware.

In 2014, Facebook bought Oculus, making Mr. Luckey a centi-millionaire. Facebook itself was then bullish about breaking into the Chinese market. That year, the Facebook founder Mark Zuckerberg swooned over a book by President Xi Jinping of China, “The Governance of China,” and recommended it to his employees.

Three years later, Mr. Zuckerberg’s company fired Mr. Luckey, who had become a Facebook executive after the Oculus deal, after it emerged that he donated to a pro-Trump group. (Mr. Zuckerberg has denied that the departure had anything to do with politics.) Mr. Luckey made what would become the most pivotal move of his career: He started an arms firm backed by Mr. Thiel’s Founders Fund, which had only just dropped language in its “vice clause” prohibiting investments in weapons.

Mr. Luckey once said his goal with Oculus was to make virtual reality “available to everyone.” A little more than a decade later, he wanted to make virtual reality available to everyone in uniform. “I strongly believe you are going to see augmented reality on every soldier’s head before you see it on every consumer’s head,” Mr. Luckey said last year. Facebook, today called Meta, is in fact now working with Anduril on a multibillion-dollar project to sell virtual reality headsets to the U.S. military.

The arc of Silicon Valley’s moral universe doesn’t seem to last longer than the next presidential election. In the end, it’s not bombs that Silicon Valley loves, but profits.

Sharon Weinberger is editor in chief of the Bulletin of the Atomic Scientists. This article originally appeared in The New York Times.