The Horizon class (French: Classe Horizon; Italian: Classe Orizzonte) is a class of air-defence destroyers in service with the French and Italian navies. They are designated as destroyers by the Italians and using NATO classification but are referred to as "frigates" by the French. The programme started as the Common New Generation Frigate (CNGF) a three-nation collaboration between France the United Kingdom and Italy to develop a new generation of air-defence warships. Differing national requirements workshare disagreements and delays led to the UK withdrawing from the project in 1999 to develop the Type 45 destroyer.