Beijing told Chinese companies that handle critical information on Sunday to stop buying products from Micron Technology, the US maker of memory chips used in phones, computers and other electronic devices. Many analysts saw the move as retaliation for Washington’s efforts to cut off China’s access to high-end chips.

In a statement from his official social media site, the Cyberspace Administration of China said it had found in a cybersecurity review that the chipmaker’s products posed “relatively serious cybersecurity problems.” The problems could “seriously jeopardize China’s critical information infrastructure supply chain” and threaten national security, he said.

China’s action is the latest flurry in an economic tit-for-tat between Beijing and Washington that is reshaping the fabric of a sprawling global microchip industry. The decision to block Micron from selling its chips to key companies could have a ripple effect on China’s supply chains, as Micron’s Chinese customers seek to replace American memory chips with local or Korean versions. South Korean chipmakers such as Samsung and SK Hynix are competitors to Micron and already do significant business with China.

Beijing launched a Micron cybersecurity review at the end of March as part of what it called a “normal regulatory measure.” The announcement came after Washington implemented restrictions in October against China’s semiconductor industry. Micron said at the time that it was “fully cooperating” with the investigation and that its business in China was operating as normal.

In a statement, the company said it was “assessing the conclusion and assessing our next steps,” adding that it “continued to engage in discussions with the Chinese authorities.”

Since the announcement in March, China has engaged in an all-out campaign to shore up its homegrown chip industry. Beijing has spent billions of dollars on self-sufficiency efforts and Chinese companies across the supply chain have moved to replace Western chips and parts.

Chinese authorities offered few clues about what they had found posed serious risks. They have also provided little information on what is required of companies during a cybersecurity review.

In a statement, a spokesperson for the US Department of Commerce said the action against Micron, “along with recent raids and attacks on other US companies, is inconsistent with claims by the PRC that it is opening its markets and committed to a transparent regulatory framework. The department will “directly engage” with Chinese officials in response, according to the statement.

But Graham Webster, editor-in-chief of the DigiChina Project at Stanford University’s Center for Cyber ​​Policy, said that among the risks was the potential for more sanctions from Washington that could insulate major Chinese companies from memory chips. Micron.

“Supply chain security includes the risk of a foreign government cutting off supply, which the US government has done in multiple ways for other semiconductors,” Webster said. She added that China’s decision may have been in part a “risk-off measure to avoid further reliance on supplies that the United States could cut off.”

Washington has urged South Korean officials to prevent their chipmakers from filling the market gap if Micron cannot sell its chips to China, The Financial Times reported. reported in April.

China passed a cybersecurity law in 2016 that outlined rules to safeguard what it called “critical information infrastructure”, which refers to technology systems in sectors including telecommunications, transportation and defense that Chinese regulators believe would be vulnerable if they failed or leaked data.

Boise, Idaho-based Micron built its first factory in China in 2007. In recent years, as U.S.-China relations have cooled, it has begun downsizing its operations, reducing the number of staff Chinese and closing some operations. In April, it had some 3,000 employees in Shanghai, Beijing and Shenzhen.

The impact of Sunday’s decision on the company could be considerable. In 2022, Micron reported $3.3 billion in sales in China, about 11 percent of its annual $30.8 billion in global sales. It was not clear how much of those sales in China would be affected by government action.