Chertoff envisions closer scrutiny from the skies, possibly through satellites and expanded use of unmanned aerial vehicles, which have proven effective on battlefields in Iraq and Afghanistan. The Border Patrol, a branch of Homeland Security, has one Predator, which has logged 228 hours and assisted in the arrests of 300 people. The agency temporarily used two other unmanned aerial vehicles last year along Arizona's border with Mexico.
Others are also pressing for increased deployment of balloons to oversee a broad swath on both sides of the border. A high-altitude airship that Lockheed is developing for the U.S. missile defense agency -- 16 times larger than the Goodyear Blimp -- would be ideal for standing vigil over the border, Kier said.
Rep. Rick Renzi, R-Ariz., is pushing a "Red Zone Defense" that would use radar-equipped tethered balloons to peer across the Southwest border to spot smugglers and illegal crossers as they left Mexico.
Los Angeles-based Northrop Grumman, which manufactures the Global Hawk unmanned aerial reconnaissance vehicle, will likely tout its expertise in unmanned aerial vehicle technology.Other potential components of Chertoff's virtual fence include battery-powered portable radar units that agents could carry in a backpack and portable sensors that could be easily moved as immigrants switch routes.
Improved seismic sensors that can pick up the rumbling of a smuggler's truck or sophisticated receivers that can ferret out a cellphone signal in the underbrush may also be part of the mix.
Bruce Walker, director of homeland security for Northrop Grumman, called the border initiative "a pretty big deal" that will "attract an awful lot of competition." But "at the end of the day," he said, only a few may have the expertise to make a serious showing.
The growing public outcry for strengthening borders could give contractors a lasting source of business, said Darren Bezdek, a manager for INPUT of Reston, Va., a market research firm that tracks federal procurement.