Abstract: Against the backdrop of intensifying global technological competition and shifting geopolitical landscapes, U.S. research integrity and research security policies have undergone a pronounced strategic transformation, aiming to address heightened competition and security challenges in scientific research. To elucidate the underlying logic and evolutionary trajectory of these policies, this study analyzed 72 core federal-level policy documents issued from 2000 to 2024 using an LDA-based topic modeling approach. The findings indicate that the United States has established a three-layered policy framework—encompassing global governance, institutional regulation, and implementation support—that comprises eight principal themes, including global research governance and risk mitigation, misconduct investigation, foreign influence and conflict of interest, and peer review and ethical standards. Over time, U.S. research integrity and security policies have shifted from a singular focus on regulating misconduct toward more multifaceted governance. Initially, policy efforts centered on addressing frequent misconduct cases and strengthening enforcement mechanisms. Since 2011, the policy landscape has expanded to emphasize a range of issues such as compliance, disclosure, peer review, and conflicts of interest. In the most recent phase, policy priorities have become more balanced, highlighting the necessity of long-term strategies that reconcile academic openness with robust security oversight. Furthermore, the study reveals notable functional and thematic variations among federal agencies responsible for formulating and implementing these policies, reflecting an increasingly specialized and collaborative approach to research governance. These insights offer a new perspective on the driving forces behind U.S. policy adjustments and serve as a valuable reference for China and other nations seeking to play a more proactive role in global research governance.