Mexicans chafed Monday at the notion that President Bush wants to send National Guard troops to help enforce the U.S.-Mexico border, even as President Vicente Fox tried to downplay the seriousness of the move. [. . .] "It's worrying," said Arturo Solis, an immigrant-rights activist in Reynosa, across the border from McAllen, Texas. "The bad thing is that the American government is insisting on confusing immigration with a criminal problem." The move reminded some historians of 1913, when President William Taft sent troops to the Texas border. Mexico was in the midst of a chaotic revolution, and Taft was warning...