Venezuelan President Hugo Chavez on Saturday urged Chile and Cuba to join him in a \"troika\" of core nations at the forefront of a new Americas bloc that excludes the United States and Canada. \"The troika has to immediately assume responsibility,\" said Chavez, one of the architects of the Community of Latin American and Caribbean States (CELAC) on the second and closing day of the group\'s inaugural meeting. But the bloc was missing two of its biggest members -- Argentina and Brazil, whose presidents Cristina Kirchner and Dilma Rousseff both left early on Saturday, with the latter appearing cool on the new grouping\'s aims. \"I think we will have to let it (the CELAC) operate for some time\" before the unknowns about its operations are ironed out, Brazilian Foreign Minister Jose Antonio Simoes told a press conference Friday. Part of the reason may be that Brazil, Latin America\'s most populous nation and its new economic and political heavyweight, already leads its own regional bloc, the Union of South American Nations (UNASUR). UNASUR, made up of Brazil and 11 of its allies, to be sure, has a smaller scope than the CELAC or Organization of American States, but there certainly could be some doubling up in UNASUR and CELAC goals and operations. Led by Chavez, CELAC delegates have gathered since Friday at a military fort for the two-day meeting of an alliance of 33 countries. The CELAC grouping was proposed by Latin American leaders in February 2010 in Mexico, more than 60 years after the start of the Organization of American States, which is based in Washington and which excludes communist Cuba. Chavez on Friday dismissed the \"old and worn-out\" OAS, suggesting CELAC would eventually take its place. According to its organizers, CELAC is designed to usher in a new era of Latin American \"independence. More than 10,000 security forces were on duty at the summit in Caracas, one of Latin America\'s most dangerous cities.