AlterNet reports: The Department of Homeland Security says it needs a fleet of two-dozen Predator and Guardian drones to protect the homeland adequately. Designed for military use, 10 of these unmanned aerial vehicles (UAVs) are already patrolling U.S. borders in the hunt for unauthorized immigrants and illegal drugs.

DHS is building its drone fleet at a rapid pace despite its continuing inability to demonstrate their purported cost-effectiveness. The unarmed Predator and Guardians (the maritime variant) cost about $20 million each. Yet DHS has little to show for its UAV spending spree other than stacks of seized marijuana and several thousand immigrants who crossed the border without visas.

Aside from a continuing funding bonanza for border security, to pursue its drone strategy DHS is also counting on the Federal Aviation Administration to continue authorizing the use of more domestic airspace by the unarmed drones. And FAA seems set to comply, having approved 35 of the 36 requests by the department’s Customs and Protection agency from 2005 to mid-2010. In congressional testimony in July 2010, the FAA said it was streamlining its authorization process for drones, including the hiring of 12 additional staff to process drone airspace requests.

While DHS is leading the way, national and local law enforcement agencies, as well as private entities, are demanding that FAA open the American skies to drone surveillance. Yet neither the FAA nor the Department of Transportation has been forthcoming in informing the U.S. public about the new robotic presence in the already congested American airways. The Electronic Frontier Foundation recently filed a suit against the transportation department for allegedly withholding information about drones in our skies.