Which document prescribes a uniform system for safeguarding classified national security information?

The correct answer is Executive Order 13526, which prescribes a uniform system for safeguarding classified national security information. This executive order, signed into effect in December 2009, provides a comprehensive framework for classifying, safeguarding, and declassifying national security information. It establishes the criteria for classifying information, the levels of classification, and the authorized methods for safeguarding this sensitive information. By focusing on standardization across agencies, this order plays a crucial role in ensuring national security while also facilitating accountability and transparency.

Other documents, while relevant to national security and information management, do not serve the same purpose as Executive Order 13526. For instance, Executive Order 12333 primarily focuses on the organization of the U.S. intelligence community and the conduct of intelligence activities rather than the safeguarding of classified information. The National Security Act lays the groundwork for national defense and security structures, but it does not specifically address the safeguarding of classified information. The Information Security Oversight Directive provides guidance on the implementation of security policies but is not a primary governing document for classifying national security information. Thus, Executive Order 13526 stands out as the definitive directive for establishing uniformity in the safeguarding of classified national security information.