Political map of Australia, New Zealand & the Southwest Pacific 17 May 1990 (Bougainville Conflict): When Papua New Guinea (PNG) gained independence from Australia in 1975, the island of Bougainville - geographically part of the Solomons - immediately attempted to secede but was persuaded to stay on in return for greater autonomy. However, tensions continued to rise over mining in Bougainville (Panguna) and in 1988 conflict broke out (Bougainville Civil War). In a nine-year war, PNG was largely expelled from the island and eventually agreed to a New Zealand-sponsored truce.