The Pentagon last year awarded a $26 million contract to Lockheed Martin for a laser program called SHiELD (Self-protect High Energy Laser Demonstrator.)

The idea is to put a laser system on aircraft with an output of about 50 kilowatts to test their ability to zap drones or cruise missiles.

"We have got tests starting this summer and the flight tests next summer," Jeff Stanley, deputy assistant secretary of the Air Force for science, technology and engineering, told reporters.

"There are still some technical challenges that we have to overcome, mainly size, weight, power."

Military laser beams are invisible to the naked eye.

By focusing a beam on a target, the technology rapidly heats it up inside, causing it to crash or explode.