The United States announced new export controls Friday aimed at restricting China’s ability to buy and manufacture high-end chips with military applications, stepping up tensions between the countries.

 The moves complicate Beijing’s push to further its own semiconductor industry and develop advanced military systems, and come days ahead of a major party congress in China at which President Xi Jinping is expected to secure a historic third term.

The rules, announced by the US Department of Commerce, include export restrictions on some chips used in supercomputing, and toughen requirements on the sale of semiconductor equipment.

The aim is to prevent sensitive technologies with military applications from being acquired by China’s military, intelligence and security services, said Commerce Department official Alan Estevez in a statement.

The rules were announced just days after the Pentagon added 13 more Chinese firms including drone manufacturer DJI and surveillance firm Zhejiang Dahua Technology to a blacklist of Chinese military-linked companies.

The manufacture and export of semiconductors has been a subject of competition between the two countries, as they battle for tech dominance.