The Government Communications Headquarters (GCHQ) is the U.K.'s electronic intelligence collection agency. GCHQ has two important missions — Signals Intelligence (known as SIGINT) and Information Assurance (IA) — both missions sharing the challenges of modern communications and working together. It is answerable to the Foreign Office and intercepts communications using ECHELON through its Composite Signals Organisation stations in the UK and elsewhere. It is also the centre for the Cyber National Technical Authority (NTA).