border. i think it requires ranging from drones to towers to use of some of the technological advantages that we have. just very briefly tell us what you think is necessary to have a secure border. >> yes, senator. a physical barrier in and of itself certainly is a military person that understands defense and defenses, physical barrier in and of itself will not do the job. it has to be really a layered defense. if you built a wall from the pacific to the gulf of mexico, you'd still have to back that up with patrolling by human beings, sensors, by observation device. but as i've said to many of the senators present, and i've said i think for three years, i believe the defense of the southwest border really starts about 1500 miles south. and that is partnering with some