The chips, which are widely used in data centers and personal computers, were acquired from resellers in China. Some were procured as components for computing systems, with many bought by the institute’s laboratory studying computational fluid dynamics, a broad scientific field that includes the modeling of nuclear explosions.

Such purchases defy longstanding restrictions imposed by the U.S. that aim to prevent the use of any U.S. products for atomic-weapons research by foreign powers. The academy, known as CAEP, was one of the first Chinese institutions put on the U.S. blacklist, known as the entity list, because of its nuclear work.

A Journal review of research papers published by CAEP found that at least 34 over the past decade referenced using American semiconductors in the research. They were used in a range of ways, including analyzing data and generating algorithms. Nuclear experts said that in at least seven of them, the research can have applications to maintaining nuclear stockpiles. CAEP didn’t respond to requests for comment.

The findings underline the challenge facing the Biden administration as it seeks to more aggressively counter the use of American technology by China’s military. In October, the U.S. expanded the scope of export regulations to prevent China from obtaining the most advanced American chips and chip-manufacturing tools that power artificial intelligence and supercomputers, which are increasingly important to modern warfare.

An expanded version of this report appears on WSJ.com.

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