Makers of unmanned aircraft have seen the value of their market soar to more than $5bn in just a few years as the Pentagon and CIA increasingly rely on drones for their operations from the mountains of Afghanistan to the deserts of Yemen.

But what was seen recently as an even bigger commercial prize, using drones for anything from helping police find lost children to delivering tacos, is now under threat – even as the domestic market is on the brink of taking off. The industry is facing a backlash in scores of US states over privacy worries.

With demand from the US military potentially reaching a plateau, manufacturers are gearing up to sell to domestic customers when commercial airspace opens up in 2015. It is a market that executives hope will be worth tens of billions of dollars.