The United Kingdom – United States of America Agreement (UKUSA, ) is a multilateral agreement for cooperation in signals intelligence between the United Kingdom, the United States, Canada, Australia, and New Zealand. The alliance of intelligence operations is also known as Five Eyes (FVEY). Much of the sharing of information is performed via the ultra-sensitive STONEGHOST network, which contains "the Western world's most closely guarded secrets". In addition to intelligence sharing, the UKUSA agreement forms the basic foundation of the Special Relationship between the UK and the USA.