The success of the U.S. semiconductor supply chain strategy hinges on whether the United States can harmonize subsidy and export control policies with its partners in the nascent “CHIP 4” initiative—Japan, South Korea, and Taiwan. Key variables, however, have received insufficient attention in Washington. Andrew Grotto and Emily Weinstein outline ally perspectives, assess the costs and risks of U.S. actions, and offer recommendations for Congress to harmonize economic security policies among U.S. allies.