civil officials and militia from Luanda and seek sanctuary in the southern provinces. From there, Savimbi continued to mount a determined insurgent campaign against the MPLA. Between 1975 and 1991, the MPLA implemented an economic and political system based on the principles of scientific socialism, incorporating central planning and a Marxist–Leninist one-party state. It embarked on an ambitious programme of nationalisation, and the domestic private sector was essentially abolished. Privately owned enterprises were nationalised and incorporated into a single umbrella of state-owned enterprises known as Unidades Economicas Estatais (UEE). Under the MPLA, Angola experienced a significant degree of modern industrialisation. However, corruption and graft also increased and public resources were either allocated inefficiently or simply embezzled by officials for personal enrichment. The ruling party survived an attempted coup d'état by the Maoist-oriented Communist Organisation of Angola (OCA) in 1977, which was suppressed after a series of bloody political purges left thousands of OCA supporters dead (see 1977 Angolan coup d'état attempt). In the same period, the civil war culminated in its climax in a tandem of engagements, particularly the Battle of Quifangondo and soon after the Battle of Cuito Cuanavale stalemate, which marked a turning point as both sides. The MPLA abandoned its former Marxist ideology at its third party congress in 1990, and declared social democracy to be its new platform. Angola subsequently became a member of the International Monetary Fund; restrictions on the market economy were also reduced in an attempt to draw foreign investment. By May 1991 it reached a peace agreement with UNITA, the Bicesse Accords, which scheduled new general elections for September 1992. When the MPLA secured a major electoral victory, UNITA objected to the results of both the presidential and legislative vote count and returned to war. Following the election, the Halloween massacre occurred from 30 October to 1 November, where MPLA forces killed thousands of UNITA supporters. 21st century On 22 February 2002, Jonas Savimbi was killed in action against government troops. UNITA and the MPLA reached a cease-fire shortly afterwards. UNITA gave up its armed wing and assumed the role of a major opposition party. Although the political situation of the country began to stabilise, regular democratic processes did not prevail until the elections in Angola in 2008 and 2012 and the adoption of a new constitution in 2010, all of which strengthened the prevailing dominant-party system. Angola has a serious humanitarian