U.S. and European officials are growing increasingly concerned about China’s accelerated push into the production of older-generation semiconductors and are debating new strategies to contain the country’s expansion.

President Joe Biden implemented broad controls over China’s ability to secure the kind of advanced chips that power artificial-intelligence models and military applications. But Beijing responded by pouring billions into factories for the so-called legacy chips that haven’t been banned. Such chips are still essential throughout the global economy, critical components for everything from smartphones and electric vehicles to military hardware.

That’s sparked fresh fears about China’s potential influence and triggered talks of further reining in the Asian nation, according to people familiar with the matter, who asked not to be identified because the deliberations are private. The U.S. is determined to prevent chips from becoming a point of leverage for China, the people said.

Commerce Secretary Gina Raimondo alluded to the problem during a panel discussion last week at the American Enterprise Institute. “The amount of money that China is pouring into subsidizing what will be an excess capacity of mature chips and legacy chips—that’s a problem that we need to be thinking about and working with our allies to get ahead of,” she said.

While there’s no timeline for action to be taken and information is still being gathered, all options are on the table, according to a senior Biden administration official. A U.S. National Security Council spokeswoman declined to comment, while a European Commission spokesperson did not immediately provide comments.

The most advanced semiconductors are those produced using the thinnest etching technology, with 3-nanometers state of the art today. Legacy chips are typically considered those made with 28-nm equipment or above, technology introduced more than a decade ago.

Senior E.U. and U.S. officials are concerned about Beijing’s drive to dominate this market for both economic and security reasons, the people said. They worry Chinese companies could dump their legacy chips on global markets in the future, driving foreign rivals out of business like in the solar industry, they said.

Western companies may then become dependent on China for these semiconductors, the people said. Buying such critical tech components from China may create national security risks, especially if the silicon is needed in defense equipment.

“The United States and its partners should be on guard to mitigate nonmarket behavior by China’s emerging semiconductor firms,” researchers Robert Daly and Matthew Turpin wrote in a recent essay for the Hoover Institution think tank at Stanford University. “Over time, it could create new U.S. or partner dependencies on China-based supply chains that do not exist today, impinging on U.S. strategic autonomy.”

The importance of legacy chips was highlighted by supply shocks that roiled companies at the height of the Covid pandemic, including Apple Inc. and carmakers. Chip shortages cost businesses hundreds of billions of dollars in lost sales. Simple components, such as power management circuits, are essential for products like smartphones and electric vehicles, as well as military gear like missiles and radar.

The U.S. and Europe are trying to build up their own domestic chip production to decrease reliance on Asia. Governments have set aside public money to support local factories, including the Biden administration’s $52 billion for the CHIPS and Science Act.

But domestic producers may be reluctant to invest in facilities that will have to compete with heavily subsidized Chinese plants. The Biden administration and its allies are gauging the willingness of Western companies to invest in such projects before they decide what action to take.

While the U.S. rules introduced last October slowed down China’s development of advanced chipmaking capabilities, they left largely untouched the country’s ability to use techniques older than 14-nanometers. That has led Chinese firms to construct new plants faster than anywhere else in the world. They are forecast to build 26 fabs through 2026 that use 200-millimeter and 300-mm wafers, according to the trade group SEMI. That compares with 16 fabs for the Americas.

Heavy investments have allowed Chinese companies to keep supplying the West, despite rising tensions between Washington and Beijing. China’s chipmaking champion, Semiconductor Manufacturing International Corp., got about 20% of last year’s sales from U.S.-based clients, including Qualcomm Inc., despite being blacklisted by the American government.

“When you think about electrification of mobility, think about the energy transition, the IoT in the industrial space, the roll-out of the telecommunication infrastructure, battery technology, that’s all — that’s the sweet spot of mid-critical and mature semiconductor,” Peter Wennink, chief executive officer of Dutch chipmaking equipment supplier ASML Holding NV, told analysts in mid-July. “And that’s where China without any exception is leading.”