Moreno Díaz, was greatly reduced. President López retained Conservative representation in his Government, however. 4 June 1978: Dr Julio César Turbay Ayala of the PL was elected to the presidency. 1982: The problems of urban terrorism and drugs-trafficking became more prevalent and led to a series of successful counter-insurgency operations, aided by an anti-guerrilla group, the Muerte a Secuestradores (MAS), that was itself associated with drugstrafficking enterprises. 30 May 1982: The PCC candidate, Belisario Betancur Cuartas, won the presidential election with 46.8% of the votes cast. However, a Liberal majority in Congress ensured that an element of consensus would remain a feature of Colombian politics. Betancur altered the country’s pro-US orientation, becoming a member of the Non-Aligned Movement. 11 June 1982: The M-19 announced the implementation of a cease-fire. 20 November 1982: A law offering a broad amnesty for guerrillas as part of an internal pacification campaign took effect. 30 April 1984: The assassination of the Minister of Justice, Rodrigo Lara Bonilla, by drugs-traffickers led to a declaration by the Government of a nation-wide state of siege as well as the enforcement of the hitherto unobserved extradition treaty with the USA. 1985-87: A campaign of assassination of Unión Patriótica (UP-a political party formed by FARC in 1985) members by paramilitary ‘death squads’ resulted in an estimated 450 deaths. June 1985: The M-19 formally withdrew from the cease-fire agreement. 6 November 1985: A siege by the M-19 at the Palace of Justice, in which 100 people (including 11 judges) were killed, resulted in the indefinite suspension by the Government of negotiations with the M-19. March 1986: An indefinite cease-fire agreement was concluded between the FARC and the Government. 9 March 1986: The large majority secured by the PL at congressional elections obliged the PCC to form the first formal opposition to a government for 30 years. 25 May 1986: Dr Virgilio Barco Vargas of the PL was elected President with 58% of the votes cast. Barco announced his intention to continue the policy of extraditing drugstraffickers to the USA; the Medellín drugs cartel began a campaign of violence in an attempt to force the abandonment of extradition. October 1987: Six guerrilla groups, including the FARC, the M-19 and the Maoist Ejército de Liberación Nacional (ELN), formed a joint front, the Coordinadora Guerrillera Simón Bolívar (CGSB). The cease-fire with the FARC had failed earlier in the year. late 1987: The Supreme Court ruled that Colombia’s extradition treaty with the USA was unconstitutional. 13 January 1989: The Government and the M-19 agreed to resume direct dialogue. March 1989: The ELN, the EPL and the FARC confirmed their willingness to participate in peace talks with the Government.