This hardscrabble Mexican border town welcomed 400 soldiers when they arrived four months ago to stop a wave of drug violence that brought daytime gunbattles to its main street. But then the soldiers themselves turned violent, townspeople say, ransacking homes and even torturing people. The frustration boiled over this week. More than 1,000 people marched through the streets carrying signs begging President Felipe Calderon for protection from his own troops. Ojinaga, across the Rio Grande from Presidio, Texas, is not alone. People in cities on the front lines of Mexico's battle against trafficking say they are increasingly frustrated with military tactics - a shift in opinion that threatens to undermine Calderon's nationwide crackdown. Mexico's National Human Rights Commission says it has documented more than 600 cases of abuse since Calderon sent 20,000 soldiers across the nation to take back territory controlled by drug lords. ...