I can see no scenario that could make this feasible. However, if the US was attacked by an outside force today, Mexico is the only real route. An enemy that was able to get the Mexicans involved on their side would be formidible, especially if the cartels were involved. Southern California, Arizona, New Mexico, Texas, Louisianna, Oklahoma, Kansas and Arkansas are vulnerable. An enemy that could push us back would have an advantage of cutting us off from a large portion of our oil supplies.

That would be the key. Isolating the gulf states and California early would take out a lot of our key industries. Success would require a massive buildup in Mexico that was ignored by our leadership. An advantage is that they would have avenues to infiltrate many key locations and sabotage our ability to act. Our highway system could be turned against us and the military would get bogged down with dealing with evacuees and sabotage. Being able to conguer everything below the Mason Dixon line and sustain the effort would be a probable defeat for our nation. It would put us with the difficult decisions that would create impossible choices.

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Lord, let me be the person my dog thinks I am.