Enclaves and exclaves are discontiguous territories of states which are located within the territory of other states. In the case of islands they may exist within the territorial waters of another state. They are a particular form of disrupting influence on territorial integrity. As such they may be a source of military insecurity, and administrative and communication problems.
When a nation refers to an extra-territorial possession which is encapsulated in another state, it refers to its exclave. The term enclave is also used for a culturally distinct area enclosed by its host country, where another language is frequently spoken, for example the Russian enclave in Shanghai after the revolution.
The number of enclaves has declined considerably since 1900. About 15 remain in Europe. Some remain in Africa and Asia, but most have been eliminated with the independence of the countries in those areas. New enclaves have been created as a result of armistice agreements (for example, West Berlin). Other well-known enclaves are Gibraltar and Hong Kong (to 1997).