The Paracel Islands are surrounded by productive fishing grounds and by potential oil and gas reserves. In 1932, French Indochina annexed the islands and set up a weather station on Pattle Island; maintenance was continued by its successor, Vietnam. China has occupied all the Paracel Islands since 1974, when its troops seized a South Vietnamese garrison occupying the western islands. China built a military installation on Woody Island with an airfield and artificial harbor. The islands also are claimed by Taiwan and Vietnam.