South of the border, down Mexico way, a new and savage revolution rages just beyond our inspection lanes. After less than five years of fighting, estimates of the dead have reached 22,000. The rate of killing accelerates each month. And Washington covers its eyes like a kid at a scary movie. Well, the Mexican narco-insurgency, in which well-armed guerrilla forces confront the authority and presence of the state, is our No. 1 security challenge. The chaos in northern Mexico has far deeper implications for our country than Islamist terror or even an Iranian nuclear capability (as grim as those threats...