Last I checked, Mexico's major air combat forces consisted of a relative handful of F-5s, Hinds, and a few hundred AFVs. Excepting the 'illegal immigrant terrorist' concept and the drug war, it's frankly not a major threat to US interests.
Japan has the ability to be a thorn in the side of US power-projection efforts in the west Pacific, but their antiship capabilities are a credible threat (Type 93s, ASM-1 and ASM-2 carried on F-1, F-2, and F-4EJ Kai aircraft) but any fixed bases (and their antimissile systems) could possibly be overwhelmed by large quantities of BGM-109 cruise missiles or conventional strikes by F-35C or F/A-18E/F aircraft using a variety of weapons to damage or destroy runways, aircraft shelters, and aircraft in the open.
Turkey is armed with 3rd-generation and late 4th-generation aircraft and 1950s/1960s-vintage MBTs, with a handful of Leopard 2A4s. It's not a huge threat to a well-equipped force.
I think he was refering to the collapse/destabilization of the mexican government through the drug wars and the rise of a failed state in americas backyard. I think it would be a significant threat to america if such a senario played out and could result in migrations from mexico into neighboring countries and wars for power on the N. American continent.
For Turkey- he may have been refering to a shift in Turkey that would result in its backing of Iran and its move away from the NATO political block. this could be an important issue for the US as it would see a rebalancing of power in the mideast in which a relatively advanced NATO nation is now on the side of Iran and theres a major shift in policy towards Israel. the process is already occuring..