What classification level is applied to information whose unauthorized disclosure could cause serious damage?

The classification level that applies to information whose unauthorized disclosure could cause serious damage is "Secret." This classification is used to protect information that, if revealed, could significantly harm national security interests or military operations.

In the context of security clearances and information handling, there are several levels of classification that prioritize the sensitivity of the information and the potential damage that could arise from its disclosure. "Secret" specifically denotes that the material is important enough that unauthorized access could lead to serious drawbacks for national interests.

This classification helps ensure that appropriate safeguards and access limitations are in place to protect sensitive information from falling into the wrong hands, thereby maintaining operational security and safeguarding national interests.