Since independence from Portugal in 1974, Guinea-Bissau has experienced considerable political and military upheaval. In 1980, a military coup established authoritarian dictator Joao Bernardo 'Nino' VIEIRA as president. Despite setting a path to a market economy and multiparty system, VIEIRA's regime was characterized by the suppression of political opposition and the purging of political rivals. Several coup attempts through the 1980s and early 1990s failed to unseat him and in 1994 VIEIRA was elected president in the country's first free elections. A military mutiny and resulting civil war in 1998 eventually led to VIEIRA's ouster in May 1999. In February 2000, a transitional government turned over power to opposition leader Kumba YALA after he was elected president in transparent polling. In September 2003, after only three years in office, YALA was ousted by the military in a bloodless coup and businessman Henrique ROSA was sworn in as interim President. In August 2005 former President VIEIRA was re-elected President in the second round of presidential polling. Since formally assuming office in October 2005, Vieira has pledged to pursue economic development and national reconciliation.