House Select Committee on China Chairman John Moolenaar has written a letter demanding the U.S. government enforce an existing export control measure designed to prevent Chinese companies from getting advanced chips produced by contract chipmakers like TSMC or Samsung Foundry. The regulation, known as the 'Foundry Due Diligence Rule,' was signed by Joe Biden in early 2025 and required chipmakers to determine their end customers. It was introduced after it was discovered that chips made by TSMC for China-based Sophgo were actually Huawei's Ascend 910B AI accelerators. The Trump administration announced in May 2025 that it would not enforce this rule, creating uncertainty. The letter states that these exports enabled Huawei to obtain millions of controlled Ascend logic dies from TSMC, using its front company, Sophgo in 2023 and 2024. Under the rule, foundries and OSAT providers exporting chips produced on 14/16nm-class process technologies or more advanced nodes must presume those devices qualify as controlled AI processors subject to a global licensing requirement, unless they meet an exemption. According to the letter, foundries have generally complied with these requirements since the rule took effect. Moolenaar asks the government to enforce the existing controls rather than introduce stricter export controls, and believes the Commerce Department's Bureau of Industry and Security could clarify its stance in two ways.