An intelligence and security organization that reports to the Foreign Secretary and works closely with the UK's other intelligence agencies (commonly known as MI5 and MI6). Its primary customers are the Ministry of Defence, the Foreign and Commonwealth Office, and law enforcement authorities, but it also serves a wide range of other government departments. It has two missions: signals intelligence (Sigint) and Information Assurance. Sigint work protects the vital interests of the nation: GCHQ provides information to support government decision‐making in the fields of national security, military operations, and law enforcement. The intelligence it provides is concerned largely with terrorism and also contributes to the prevention of serious crime. Information Assurance helps keep the government communication and information systems safe from hackers and other threats. It also helps those responsible for the UK's critical national infrastructure (power, water, communications, etc.) to keep their networks safe from interference and disruption.