PALMDALE, Calif.  To help spot and track smugglers, the Homeland Security Department is expanding its use of drones, the unmanned aircraft widely used in Iraq and other war zones, beyond the Mexican and Canadian borders to the Caribbean and possibly other seas.

The department, through its Customs and Border Protection division, already operates five of the aircraft, known as the Predator B, along the Southwest border from a base in Arizona and the Canadian border from an installation in North Dakota.

Like the drones used by the military, these drones can fly long ranges at high altitudes and are difficult to detect. But the drones that have been used at the border since 2005 are for surveillance and tracking and do not carry weapons.

The department on Monday unveiled a new drone loaded with special radar, cameras and sensors. Built for $13.5 million by General Atomics Aeronautical Systems here, it is designed for maritime use. It features wide-range radar that gives a more sweeping view of the ocean than any of the government’s fleet of manned aircraft.