What is a critical factor when sharing classified information with others?

The critical factor when sharing classified information with others is that it should only be shared with individuals who possess the appropriate security clearance and a legitimate need to know the information. This principle ensures that sensitive data is protected from unauthorized access, reducing the risk of compromise that could lead to national security threats.

The need-to-know basis is a fundamental aspect of information security; it not only maintains the confidentiality of classified materials but also fosters accountability among personnel who handle such information. This adherence to security protocols is vital in safeguarding operational integrity and preventing unauthorized disclosures that could harm interests.

This principle is distinctly different from the other approaches mentioned, which either undermine security (like unrestricted access or public availability) or misinterpret the appropriate channels for communication. So, sharing classified information based on a need-to-know criterion is essential for maintaining security and compliance with classification guidelines.