China slammed nuclear submarine cooperation between the United States, the United Kingdom and Australia, calling it a grave threat to regional peace and stability on September 16. The three countries announced an Indo-Pacific diplomatic, security and defense cooperation pact on September 15, under which the U.S. and the UK will export "highly sensitive" nuclear submarine technology to Australia. Chinese Foreign Ministry spokesperson Zhao Lijian told a regular news briefing in Beijing that the countries' move gravely undermines regional peace and stability, intensifies the arms race, and harms the international non-proliferation efforts.