Gov. Rick Perry’s plan to activate 1,000 Texas National Guard troops for duty near the border with Mexico will do little to ease the crisis caused by the arrival of 57,000 unaccompanied minors from Central America. More significant to addressing the problem is enlisting the governments of Mexico, El Salvador, Honduras and Guatemala to better enforce their own borders and discourage adults and children from attempting the dangerous trip northward. No show of force can stop them from crossing. Once they’re here, U.S. law requires that they enter a legal process intended to ensure they’re protected from predators in their...