In another recent document, U.S. diplomats voiced concerns that Mexican drug dealers could end up buying certain high-tech weapons that Russia had sold to Venezuela. Such weapons are capable of shooting down U.S. combat helicopters.

The document said U.S. officials feared that members of the Revolutionary Armed Forces of Colombia (FARC) would obtain the weapons for the Mexican cartels.

FARC guerrilla members have been reported in Mexico for the past ten years and are suspected of helping one of the Mexican drug cartels kidnap a high-level official of the National Action Party, officials said.