Concept of Operations for CBP’s Predator B Unmanned Aircraft System” was submitted to Congress on June 29, 2010 shows that, not only is the agency planning to sharply increase the number of Predator drones it flies and the amount of surveillance it conducts by 2016 but it has considered equipping its Predators with “non-lethal weapons designed to immobilize” targets of interest. . The report was recently obtained by the Electronic Frontier Foundation via a FOIA request.
One assumes the drones would be assigned to the Southwest border but the detail "airspace access" is redacted suggesting that DHS may want to fly the weaponized drones over any US airspace. To quote the report;
Additional payload upgrades could include expendable or non-lethal weapons designed to immobilize TOIs. (Targets of interest)