Which of the following is NOT considered a source for classification?

Public domain information is not considered a source for classification due to its availability and accessibility to the general public. Information in the public domain can be freely used, shared, and distributed without any restrictions. As a result, it does not meet the criteria for classification, which includes the need to protect information from unauthorized disclosure.

In contrast, military operations, foreign government information, and weapons of mass destruction all involve sensitive details that require protection due to national security interests. These categories typically contain information that, if disclosed without proper authorization, could jeopardize national defense, international relations, or public safety, thus necessitating their classification under appropriate guidelines.