Which level of classification is the most sensitive?

The most sensitive level of classification is Top Secret. This classification is reserved for information that, if disclosed, could cause exceptionally grave damage to national security. It encompasses the highest degree of sensitivity and is critical for protecting information that involves national defense, intelligence sources, methods, and other vital secrets necessary to the framework of national security.

Top Secret information requires stringent safeguarding measures and protocols due to the potential consequences of its unauthorized disclosure. The classification levels below Top Secret—Confidential and Secret—are still sensible but pertain to information that would cause damage or serious damage if exposed. Restricted Information is not a formal classification level per se but generally refers to data that it may be unclassified but still requires controlled access due to its nature. Therefore, Top Secret stands out as the highest and most sensitive classification level.