The export-variant Predator, General Atomics says, should deal with some of those concerns. It will have no “hard points” to attach missiles and would be deliberately engineered to make adding new weaponry impossible, it says.

Retailing at $3-4 million an item, the unarmed export UAV is way cheaper than most equivalent aircraft, Ames said.

“There are countries that for a long time have been asking for Predator,” he said. “It (the export variant) opens that up to us.”

Other U.S. defense firms are also investing growing quantities of their own money in new and innovative UAVs. Boeing recently test-flew its prototype “Phantom Eye”, a high-altitude drone capable of staying airborne for days at a time.

Even if foreign markets remain sometimes off-limits, the Pentagon is seen as still keen to expand the use of UAVs into new areas. Lockheed Martin says it is investing in unmanned technologies and plans to compete for a future U.S. Navy contract to build a next-generation drone that will operate from aircraft carriers.

That contest is also likely to include Northrop, maker of the X-47B, a U.S. Navy program that is demonstrating some of the initial capabilities that would be packed on the future carrier UAVs.

Officials say Britain is also increasingly interested in naval drones to operate from carriers as well as a range of smaller warships. But BAE’s Rowe-Wilcocks says the real growth area will ultimately be the civilian sector.

Within a decade or so, he believes unmanned aircraft will routinely operate in European air space, providing surveillance for law enforcement agencies, maritime patrol and a host of other functions.

“The test will be whether the public will accept unmanned aircraft overhead in the way they accept those with someone in the cockpit,” he says. “At this stage, I think we’re more or less there technologically. It is really going to be a regulatory and particularly cultural challenge.”