This term is used constantly over the course of any given newscast. Many viewers do not comprehend that violations of our national security are serious crimes. They understand that murder, rape, robbery etc. are unlawful, but I doubt many could cite an example of a violation of national security and link it to what they are hearing on the news.

A list would be helpful:
Unauthorized disclosure of classified information
Data breaches
Terrorism
Espionage
Cyber threats

Others?