In return, Argentina asked the U.S. for the cession of southern Chile to Argentina. Later, Chile and the United States averted the war. Pactos de Mayo The Pactos de Mayo are four protocols signed in Santiago de Chile by Chile and Argentina on 28 May 1902 in order to extend their relations and resolve its territorial disputes. The disputes had led both countries to increase their military budgets and run an arms race in the 1890s. More significantly the two countries divided their influence in South America into two spheres: Argentina would not threaten Chile's Pacific Coast hegemony, and Santiago promised not to intrude east of the Andes. Snipe incident In 1958 the Argentine Navy shelled a Chilean lighthouse and disembarked infantry in the uninhabitable islet Snipe, at the east entrance of the Beagle Channel. Killing of Hernán Merino Correa The Laguna del Desierto incident, in Argentina called also Battle of Laguna del Desierto occurred between four members of Carabineros de Chile and 90 members of the Argentine Gendarmerie and took place in zone south of O'Higgins/San Martín Lake on 6 November 1965, resulting in one Lieutenant killed and a Sergeant injured, both members of Carabineros, creating a tense atmosphere between Chile and Argentina. Operation Soberanía Trouble once again began to brew in the 1960s, when Argentina began to claim that the Picton, Lennox and Nueva islands in the Beagle Channel were rightfully theirs, although this was in direct contradiction of the 1881 treaty, as the Beagle Channel Arbitration, and the initial Beagle Channel cartography since 1881 stated. Both countries submitted the controversy to binding arbitration by the international tribunal. The decision (see Beagle Channel Arbitration between the Republic of Argentina and the Republic of Chile, Report and Decision of the Court of Arbitration) recognized all the islands to be Chilean territory. Argentina unilaterally repudiated the decision of the tribunal and planned a war of aggression against Chile. In 1978 Direct negotiations between Chile and Argentina in 1977-78 failed and relations became extremely tense. Argentina sent troops to the border in Patagonia and in Chile large areas were mined. On 22 December, Argentina started Operation Soberanía in order to invade the islands and continental Chile, but after a few hours stopped the operation when Pope John Paul II sent a personal message to both presidents urging a peaceful solution. Both countries agreed that the Pope would mediate the dispute through