The US Commerce Department restricted exports to entities that it says recruited Western pilots to train Chinese military personnel, as well as some that helped develop hypersonic weapons.

They were among 43 groups added Monday to the department’s so-called Entity List, which covers national-security threats.

“It is imperative that we prevent China from acquiring US technologies and know-how to enable their military modernization programs,” Matthew Axelrod, assistant secretary for export enforcement, said in a statement.

Aviation Industry Corporation of China 612 Institute was among those added for seeking US items to help Beijing’s military modernization, with ties to activities including design and manufacturing of air-to-air missiles.

Shanghai Supercomputing Technology was added for supporting the operation of supercomputers located in China, specifically by offering cloud-based supercomputing capabilities to support hypersonics research.

The US action over recruiting pilots follows reports last year, including in the Wall Street Journal in December, that China’s military had sought to enlist veteran Western pilots to improve its ability to fly planes from aircraft carriers, which could be useful in the event of a conflict with the US.

In addition to 31 Chinese entities, the department added five firms from the United Arab Emirates, four from Pakistan, three from South Africa, two from the UK, and one each from Kenya, Laos, Malaysia, Singapore and Thailand.

Entities were also added for contributing to Pakistan’s ballistic-missile program and other weapons.

The Entity List is a roster of people and organisations to which US companies can’t export technology without first securing a license, which requires a strong case for why an exception should be made.

The list has traditionally covered foreign scientists and shell companies, and it’s been used to cut off sales to terrorist groups. In recent years, the list has expanded to include more than 600 Chinese entities, including large companies such as computer server maker Inspur Group and chipmaker Semiconductor Manufacturing International Corp.