A display booth for Aliyun, Alibaba Group Holding Ltd.'s cloud computing unit, at Alibaba's annual November 11 Singles' Day online shopping event in Shenzhen, China in 2016. (Qilai Shen/Bloomberg)

Forget aluminum and steel. The real trade war may be waged in Silicon Valley.

At first blush, President Trump’s aluminum and steel tariffs, imposed Thursday, have little to do with the cutting-edge technologies being built in the United States’ innovation hub.

But some Silicon Valley executives fear that the protection of an old-school industry, one that accounts for just 2 percent of global trade, could be a prelude for a much broader clash with China over the theft of technologies that are driving the future of the global economy. Such a conflict would have a profound impact on how Silicon Valley does business with a critical, if elusive, trading partner.

The dispute is already underway. In August, the Trump administration initiated a sweeping investigation into Chinese trade practices, including whether Chinese firms are investing in U.S. companies to steal their technology and whether they are forcing joint ventures, pressuring American companies that invest in China to transfer technology to a Chinese partner, or hacking U.S. companies’ software.

If the investigation finds that China violated trade laws, the executive branch could issue sanctions against China that go far beyond tariffs. The results of the Trump administration’s investigation could change what many Silicon Valley companies, striving to do business in China, have long seen as the price of entry.

“Everyone has their hair on fire over the steel and aluminum trade enforcement tariffs that are pretty standard stuff,” said Lori Wallach, director of Global Trade Watch for the government watchdog group Public Citizen, which opposes trade agreements that it says benefit companies over people. “But the amount of money at stake with the steel and aluminum dumping looks like penny slots compared to the claims of China’s technology theft that the administration is investigating.”

Michael Wessel, a member of the U.S.-China Economic and Security Review Commission, a watchdog panel set up by Congress in 2000, said that “there’s no question they will find violations.”

Experts say the resignation of National Economic Council Director Gary Cohn — a free-trade proponent who had taken issue with the inquiry, known as a Section 301 investigation — could speed things up, and the results are expected in the next several weeks, according to a person familiar with the matter.

Computer services were the world’s fastest-growing service export from 1995 to 2014, according to the World Trade Organization.

Sanctions, which are issued by the executive branch, could go beyond tariffs to include heightened review or possibly barring Chinese government officials, state-owned enterprises or any investor receiving money from the Chinese government from acquiring an interest in a U.S. company with sensitive technology. Such sanctions could block the sale or use of any technologies that were stolen.

They could even go so far as requiring U.S. stock exchanges to limit who can list in a U.S. market. Penalties would be more severe if they found that the Chinese government was complicit in the actions of its companies.

In recent years, Chinese capital has flooded into Silicon Valley, infusing start-ups with much-needed cash while raising questions about investors’ goals and government ties. At the same time, U.S. technology giants — including Google, Facebook, Amazon.com, Uber and Airbnb — have bent over backward to enter the massive Chinese market, largely with limited success. Google and Facebook do not operate in China; Uber’s Chinese operations are now controlled in part by its Chinese competitor, Didi Chuxing; and Amazon operates cloud data centers there, but its presence is dwarfed by Alibaba’s cloud operation. (Amazon chief executive Jeffrey P. Bezos owns The Washington Post.)

China’s technology industry has also exploded. Alibaba, Tencent and Baidu, often referred to as the Amazon, Facebook and Google of China, have become multibillion-dollar multinationals. Each maintains a sizable investment arm in Silicon Valley.

Today, advancement in industries such as robotics, self-driving cars and artificial intelligence is a matter of national policy in China. The policy, called Made in China 2025, identifies a strategy for acquiring foreign technology to build the capacity of Chinese companies.

Silicon Valley entrepreneurs say Chinese investors can be valuable partners, sometimes seen as fixers who can offer assistance in breaking into an alluring but opaque market.

But doing so often requires that the start-up engage in a complicated balancing act and navigate a minefield of security risks. Start-ups debate whether to offer board seats to Chinese investors, fearing the access will give them too much visibility into their technology, leading to the software being copied or making its way to the Chinese government.

Other companies have struggled with rules in China that require American companies entering the Chinese market to form a joint venture with a Chinese partner to which they are required to transfer technology, as well as requirements that data must be stored locally on Chinese servers. (Many countries, including Russia, Brazil and Germany, have such laws requiring local data storage.)

Apple recently announced it would move iCloud accounts registered in mainland China to state-run Chinese servers, along with the digital encryption keys needed to unlock them, as a concession to the Chinese government.

U.S. lawmakers and officials have become increasingly concerned about the security risks of Chinese investment. Last year, the Pentagon warned in an official report that the U.S. government needed to impose stricter controls over Chinese investment because it was leading to the transfer of promising military technologies to China.

Legislation that would increase scrutiny over such deals is pending in Congress. The legislation would expand the powers of the Committee on Foreign Investment in the United States, or CFIUS, the government body that reviews foreign mergers for potential threats to national security. CFIUS’s greater scope would allow for review of foreign deals beyond the military sphere and include a broader array of cutting-edge technologies.

Last year, President Trump made the rare move of blocking the purchase of chipmaker Lattice Semiconductor by a Chinese-backed investor. And last week, CFIUS held up the acquisition of U.S. chipmaker Qualcomm by Singapore-based Broadcom, citing security concerns related to China’s influence over the creation of a 5G cellular network.

In restarting negotiations over the North American Free Trade Agreement, Wallach said, the administration has also taken issue with laws requiring localized data storage. She said that data storage and other technology issues are the new frontier for global trade battles.

Wessel said that one challenge for the investigation is that tech companies are hesitant to come forward to share information about technology transfers, out of concerns that a new disclosure could prompt shareholder lawsuits.

Carmen Chang, chairman and head for Asia investments at the venture capital firm New Enterprise Associates, said she watched Trump’s move closely this week with an eye toward what might come next for Silicon Valley. The mounting tensions risk doing damage to a relationship that is critical for both sides, she said.

“Everyone in Silicon Valley is thinking about what this might be a precursor to,” Chang said. “It’s a serious problem, but we are concerned that the reaction from Washington will be like taking a meat cleaver to it.”