With everything being revealed by the WikiLeaks revelations, it seems that Felipe Calderon made a point to then U.S. Ambassador Dennis Blair that the increased U.S. presence in Latin America was needed to counter the influence of "our friend" Hugo Chavez in the region.
The point of this is not that Wiki leaked, but that Calderon is making it clear that Mexico see Venezulean influence as a contributor to regional imbalance. They are concerned about losing parts of Mexico to the cartels. The implication is that Chavez has a hand in what is happening in Mexico..."Dontcha think" that has to include arms (that do not come from the U.S. side of the border).
This is unfolding.