In 1990, the National Party government took the first step towards dismantling discrimination when it lifted the ban on the ANC and other political organisations. It released Nelson Mandela from prison after 27 years' serving a sentence for sabotage. A negotiation process followed. With approval from the white electorate in a 1992 referendum, the government continued negotiations to end apartheid. South Africa also destroyed its nuclear arsenal and acceded to the Nuclear Non-Proliferation Treaty. South Africa held its first universal elections in 1994, which the ANC won by an overwhelming majority. It has been in power ever since. The country rejoined the Commonwealth of Nations and became a member of the Southern African Development Community (SADC).