This paper examines the growing cyber threats facing the United States' vital infrastructure, particularly those posed by state-sponsored threat actors. It discusses the significant risks these threats pose to economic stability and national security. It highlights the difficulties in protecting U.S. critical infrastructures from the constantly advancing and complex strategies employed by cybercriminals, who take advantage of the fundamental flaws in traditional security models. Furthermore, the paper presents an overview of the cyber threat environment in the United States and explains the strategies, tactics, and fundamental values for implementing Zero Trust security in critical infrastructure sectors. The study underscores the importance of technological solutions, security policies, governance, risk management, and the role of human elements in creating a robust cyberinfrastructure. Adhering to internationally recognized standards such as NIST, ISO/IEC 27001, and OWASP, this framework aims to bolster U.S. cyber defenses against a broad spectrum of cyber threats, thereby enhancing economic stability, national security, and the continuous delivery of critical services. The findings of this research have significant implications for the future of U.S. critical infrastructure security, emphasizing the need for a proactive and comprehensive approach to cybersecurity in the face of evolving threats.