Bougainville is an island in the Pacific Ocean that belongs to Papua New Guinea since the independence of that country in 1975. In September 1975 several Bougainville leaders declared independence of the island as the Republic of North Solomons. The declaration was recognized by no other state. In August 1976 the secessionist leaders and the government of Papua New Guinea reached a reintegration deal.
Starting from 1988, however, tensions mounted. This eventually led to what is known as the Bougainville Civil War. In 1989, as "a copper mine co-owned by an Australian mining company and the PNG government became the focus of conflict," peacebuilding organization specializing in the Bougainville conflict Conciliation Resources writes in this report. "The introduction of Australian and New Guinean workers caused resentment and the exploitation of the mine became increasingly intertwined with issues of indigenous identity. What began as a campaign of sabotage," the report continues, "escalated into a violent campaign for independence, resulting in the formation of both the Bougainville Revolutionary Army and a government-backed militia."
In 2001, Papua New Guinea and a Bougainville provisional goverment agreed to put an end to the armed conflict. The deal included autonomy for Bougainville, regular elections starting from 2005, and a referendum on independence between June 2015 and June 2020.
In 2016, the governments of Bougainville and Papua New Guinea reached a provisional agreement to hold the vote on 15 June 2019.