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.