The background is the quiet confrontation that saw, on one side, Brazil support Christine Lagarde against Mexico's Agustin Castens for the top job at the IMF, and on the other Mexico's refusing to support the ultimately successful candidacy of Brazil's José Graziano da Silva for the FAO's directorship.
The foreground is Chile's Sebastián Piñera's two-day visit to Mexico, during which various agreements were signed and above all where the two announced they would collaborate on relations with Asia.
Like much diplomacy, especially Presidential diplomacy in Latin America, declarations are one thing, action something else altogether. In the current context, the noises from Mexico, however, have a deeper meaning. They point to the consolidation of a liberal/Pacific bloc in Latin America, made up of Mexico, Colombia, Peru, and Chile. This bloc has close links--trade, political and even military--with the US, and it looks frankly at Asia, mostly--though this is less true of Mexico--without much apprehension.
From Brazil's standpoint, this is bad, bad, bad, mostly because it challenges five basic tenets of its current foreign policy: 1) it keeps the US, albeit indirectly, very much in South America's picture and 2) it brings Mexico into it, both of which play against Brazil's attempt to carve South America out for itself; 3) it pointedly asserts that one can play a liberal card and win, which is very much at odds with Brazil's outlook; 4) it suggests that one should accept and capitalize on a global division of labour in which Latin America is a provider of natural resources and agricultural products, something that Brazil still refuses to do, in spite of the desindustrialization that has taken place in the country since the 1990s; and 5) it sinks the idea that Brazil could represent a unified region in global institutions.
Obviously, the news is worse for Chavez' Alba, which is even more deeply caught up in backward rhetoric, schizophrenic foreign policy--where deep and un-diversified dependence primary good exports is mixed with attempts at autonomous action-- and anti-US outlook, when the US is simply not a dominant force in the region any more.
Now, Humalla may change the game a bit if he clearly aligns Peru with Brazil, but if he is anywhere as pragmatic as his campaign has suggested, he will play along and join Andean countries' movement away from Brazil and its Atlantic dependencies.