 for those considering crossing our border. Speaking during a visit to Tucson, Arizona today, polling shows immigration is on many voters' minds. There's also growing concerns about who's coming in. Fox's Matt Finn. Border security and national security has been a major concern for quite some time now, and it seems like it's only becoming more heightened with this new information that DHS says it has identified more than 400 migrants from Central Asia who were brought into the U.S. through an ISIS-related network.