North American Command: U.S., Canada, Mexico
Have you ever heard of the Northern Command, also known as Norcom? Probably not.
Have you heard of moves to integrate the United States, Canada, and Mexico into one judicial authority? Probably.
Here is the description of Norcom on Wikipedia.
United States Northern Command (USNORTHCOM) is a Unified Combatant Command of the U.S. military tasked with providing military support for civil authorities in the U.S., and protecting the territory and national interests of the United States within the contiguous United States, Alaska, Canada, Mexico (and the air, land and sea approaches to these areas).
USNORTHCOM was created on April 25, 2002 when President George W. Bush approved a new Unified Command Plan, following the 11 September 2001 attacks. USNORTHCOM went operational on October 1, 2002.
The support that USNORTHCOM provides to civil authorities is legally limited by the Posse Comitatus Act, which sets some limits on the role of the U.S. military in civilian law enforcement. However, in case of national emergency, natural or man-made, its Air Forces Northern National Security Emergency Preparedness Directorate will take charge of the situation or event.