This paper examines the evolving framework of domestic Artificial Intelligence (AI) governance in the United States and its implications for national security and global stability. As AI technologies advance rapidly, the U.S. faces increasing pressure to balance innovation, ethical regulation, and security imperatives. The study explores key policy mechanisms, institutional responses, and strategic initiatives shaping AI governance, including federal oversight, private-sector collaboration, and defense applications. It also assesses how domestic governance decisions influence international norms, competition, and cooperation in AI development. Through a multidisciplinary analysis combining policy review and security studies, the paper highlights the dual challenge of maintaining U.S. technological leadership while mitigating geopolitical risks and ethical concerns. The findings underscore the need for a coherent AI governance strategy that safeguards national interests, promotes responsible innovation, and supports a stable international AI order.