The US navy has used a powerful laser cannon to shoot down drone aircraft and will start deploying the weapon on its ships, saying it represents the future of warfare.

"The future is here," said Peter Morrison at the Office of Naval Research's Solid-State Laser Technology Maturation Programme.

The weapon, known as the Laser Weapon System or Laws, has so far only been used to shoot down drones in testing areas but is being billed as a step towards transforming warfare. Since it runs on electricity it can fire as long as there is power at a cost of less than US$1 dollar per shot, says the navy.

"Compare that to the hundreds of thousands of dollars it costs to fire a missile and you can begin to see the merits of this capability," said Rear Admiral Matthew Klunder, chief of naval research. The prototype, which one official said cost $31m-$32m to make, will be installed aboard the USS Ponce, which is being used as a floating base in the Middle East, sometime after October 2013.

Klunder said the navy expected that someday incoming missiles would not be able to "simply outmanoeuvre" a highly accurate laser beam fired at the speed of light.

A report from the Congressional Research Service praised the laser technology but noted drawbacks, including the potential it could accidentally hit satellites or aircraft. Weather also affects lasers.

"Lasers might not work well, or at all, in rain or fog, preventing lasers from being an all-weather solution," it said in a report issued on 14 March.