This classification is to be used with the utmost restraint. Examples of exceptionally grave damage include armed hostilities against the United States or its allies disruption of foreign relations vitally affecting the national security the compromise of vital national defense plans or complex cryptologic and communications intelligence systems the revelation of sensitive intelligence operations and the disclosure of scientific or technological developments vital to national security. The test for assigning Top Secret classification is whether its unauthorized disclosure could reasonably be expected to cause exceptionally grave damage to the national security. Top Secret refers to national security information or material which requires the highest degree of protection. These classification categories are defined as follows: No other categories are to be used to identify official information or material requiring protection in the interest of national security, except as otherwise expressly provided by statute. Information or material which requires protection against unauthorized disclosure in the interest of the national defense or foreign relations of the United States (hereinafter collectively termed national security) is classified Top Secret, Secret or Confidential, depending upon the degree of its significance to national security. § 3a.11 Classification of official information.