The U.S. Treasury has finalized rules restricting American investments in China's semiconductor, AI, and quantum sectors due to national security threats. Effective January 2, 2024, U.S. entities must report certain transactions and are prohibited from investments that could enhance China's military capabilities. This follows President Biden's executive order aimed at limiting financial aid to countries of concern, amid bipartisan support in Washington. The Treasury emphasizes that investments should not bolster technologies that threaten U.S. security, with violations leading to significant fines.