Why be concerned? Because neither Mexico nor Canada recognizes inherent, natural rights. All of their "rights" are actually privileges, granted by the government, and subject to removal at the government's whim. A North American Union would effectively eliminate the Bill of Rights. Since neither Mexico nor Canada recognizes the right to keep and bear arms, it's a virtual certainty that the Second Amendment would be the first right to be eliminated.
JPFO alerts us to the dangers of the nascent North American Union.
[Via John Schaefer]