Watch: US Navy uses laser to shoot down drone

The US says it has successfully tested a laser that can take down enemy planes and drones.

Video uploaded to YouTube by the US Navy shows its ship the USS Portland firing a red beam at a drone flying nearby. The drone catches fire.

In a statement, the US Navy said it was "redefining war at sea".

"Amphibious transport dock ship USS Portland successfully disabled an unmanned aerial vehicle (UAV) with a Solid State Laser - Technology Maturation Laser Weapon System Demonstrator (LWSD)," it said.

The test took place on May 16.

"LWSD is a high-energy laser weapon system demonstrator developed by the Office of Naval Research and installed on Portland for an at-sea demonstration. LWSD's operational employment on a Pacific Fleet ship is the first system-level implementation of a high-energy class solid-state laser."

LWSD is the culmination of nearly six decades of research into laser warfare, and developed by contractor Northrup Grumman. The US Navy calls them "directed energy weapons", or DEWs.

"DEWs are defined as electromagnetic systems capable of converting chemical or electrical energy to radiated energy and focusing it on a target, resulting in physical damage that degrades, neutralises, defeats, or destroys an adversarial capability," the Navy said.

"Navy ships face an increasing number of threats in conducting their missions, including UAVs, armed small boats, and adversary intelligence, surveillance and reconnaissance systems. The Navy's development of DEWs like the LWSD, provide immediate warfighter benefits and provide the commander increased decision space and response options."

The advantage of using a laser, rather than a physical projectile, was explained by Lt Cale Hughes in 2017 at a previous test.

"It is throwing massive amounts of photons at an incoming object," he told CNN. "We don't worry about wind, we don't worry about range, we don't worry about anything else. We're able to engage the targets at the speed of light."

Each shot reportedly only costs about as much as a gallon of diesel - about $5. Traditional missiles can cost hundreds of thousands - or even millions - of dollars.