NAFTA has extended from economic integration into a political and regional security pact which has been achieved through the Security and Prosperity Partnership (SPP) of North America, Plan Mexico, as well as other initiatives. Various pieces of legislation and reports, along with influential individuals have called for closer trilateral cooperation regarding common rules for immigration and security enforcement around the perimeter of the continent. A major part of the U.S. security agenda already includes the defense of North America, but a full blown security zone would bring Canada and Mexico further under its control. A Fortress North America poses a serious threat to our sovereignty and would mean the loss of more civil liberties.
Plans for a North America security perimeter might have seemed like a pipe dream just a short time ago, but it could become a reality sooner than one thinks. Some believe that a perimeter approach to security would be a more effective way of providing safety while ensuring the free flow of trade and investment. For those pushing for deep continental integration, this move is seen as the next logical step. A recent article from the Toronto Star, Canada warms to idea of a tougher 'perimeter' suggests that Canadians might now be ready to debate the concept of perimeter security. David Biette who specializes in U.S.-Canada relations and is a member of the Woodrow Wilson Center stated that a, "Perimeter is no longer a dirty word. It's beginning to come up again, at least in academic circles." He went on to say, "Canada held back when it first came up and I can certainly understand why. There was still such bad feeling left over on free trade and what that might mean for Canadian sovereignty that perimeter security was just not palatable to Canadians." Biette also added, "You ask yourself, 'What would a mutually improved relationship look like?' and really, there is nothing else. Perimeter is the one big thing – the last truly huge step on the horizon." A North American security perimeter would be one of the final steps needed in the creation of a North American Union.
full article http://beyourownleader.blogspot.com/2010/01/north-american-security-perimeter-on.html

I think it's a done deal, and has been for quite a while now.