What classification level would cause identifiable damage to national security?

The classification level designed to protect information that, if disclosed, could cause identifiable damage to national security is "Secret." Information classified at this level is deemed sensitive and is guarded to prevent harm to national interests.

To clarify the specific levels: Top Secret information would lead to exceptionally grave damage, while Secret information is associated with serious damage. Confidential information is related to less severe damage. Sensitive But Unclassified is a separate category, which, while potentially sensitive, does not meet the threshold for classification under national security standards.

In summary, while various levels of classification exist, the "Secret" classification is the appropriate designation when considering information that could cause identifiable harm to national security.