HOUSTON, Texas -- A dozen U.S. Predator aircraft will be based at Houston's Ellington Field for use in homeland security and border patrols.

Predators are unmanned aircraft that can carry missiles and can stay airborne for 24 hours. They can be operated by ground control or satellite. They can be used to locate targets and either fire their own Hellfire missiles or be followed up by other aircraft.

Perry said the 12 Predators at Ellington will be used to patrol such assets as the Southeast Texas ports and petrochemical complex and NASA's Johnson Space Center. Perry said they'll also be used to patrol the border with Mexico.

DeLay -- who's a Sugar Land Republican -- says the aircraft would used to monitor illegal immigration. Perry says they'd also be used as a bargaining chip with the independent federal base-closing commission to keep the 147th Fighter Wing at Ellington.