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.