/ˈnæʃənl sɪˈkjʊrəti ˌklæsɪfɪˈkeɪʃən/ – Phrase
Definition: khu vực bảo mật những tư liệu liên quan đến an ninh quốc gia.
A more thorough explanation: “National security classification” refers to the process of designating information as classified in order to protect national security interests. This classification system is typically used by governments to control access to sensitive or classified information that, if disclosed, could harm national security.
Example: The government agency classified the document as “top secret” due to its importance to national security.