I knew there was something in the works for enforcing the border with a military presence, but I thought it was due to the increasing violence and not potential Mexican government collapse.

I thought the primary concern was the Zetas, former anti-drug commandos (trained by US), turned drug enforcers and now new Cartel owners. They are very strong in Laredo, El Paso and other border locations. Recent reports have them setting up cells in most major cities. Law Enforcement isn't equipt to handle them.