America sees long (up to five years) endurance UAVs as salvation in the event of a space satellite apocalypse. The U.S. military is concerned about American dependence on space satellites, particularly the GPS birds. The U.S. Navy is particularly disturbed about this, because their warships depend on satellite communications while at sea. They can get by with the older wireless communications, but this form of transmission is very slow, and the navy has to move a lot more data these days in order to operate effectively.
The U.S. Air Force believes China is developing the ability to carry out a major attack on American military satellites (the "satellite apocalypse"). Their proposed solution is to take GPS out of orbit, and make it portable. High flying aircraft, UAVs or blimps would take over satellite communications, surveillance and navigation (GPS) chores, although for smaller areas. This would make GPS, and other satellite functions, more resilient to attack.
This where the navy and the long endurance UAVs come in. There are several models in development. They all are similar in concept. They are lightweight, use solar panels to drive the electric motors day and night and power the communications relay or sensors (cameras and such) and fly at high altitudes (20,000-30,000 meters, above the weather).