We may never know whether Cuba attacked American diplomats with microwave weapons—but we do know similar devices exist. The US Department of Defense’s Joint Non-Lethal Weapons Directorate, along with a host of private arms companies, has spent decades testing everything from long-range wireless Taser bullets to sonic guns that can disable a car engine from 150 feet away. The one requirement: These weapons must emit less than 10,000 joules, the amount of energy it takes to kill a person. Bombs incite wars, the thinking goes—but North Korea miiight forgive the “accidental discharge” of a directed-energy laser pulser (also, as it happens, in the works).

1. Laser-Induced Plasma Effect

Still in the lab, this blaster employs two lasers. The first pulses on and off to dislodge atmospheric electrons and spin up plasma, while the second beams straight into the resulting ball of ionizing gas to release an ear-splitting burst of sound energy.

2. Carbon Nanotube Thermophone

Instead of a traditional loudspeaker’s array of cones, coils, and magnets, this lightweight projector pushes heat currents through cylinders of pure, finely twisted carbon. Rapidly warming and cooling these tubes creates noise, a technique that, the Defense Department hopes, could one day imbue tiny drones with the power to scream “Drop your weapons, enemy scum!”

3. Pre-Emplaced Electric Vehicle Stopper

At Tinker Air Force Base in Oklahoma, the DOD is experimenting with electrified speed bumps. When the ground panels detect incoming wheels, they emit high-voltage pulses that disrupt the vehicle’s engine—but won’t electrocute the passengers, giving guards more time to investigate suspicious visitors.

4. Variable Kinetic System

Once a Darpa science project, PepperBall’s AR15-esque gun can fire 180 rounds of micro-­pulverized burning irritant (or stink bombs or inky liquid) before reloading. First military deployment: Afghanistan.

Jeremy Perrodeau

5. Maritime Vessel Stopping Occlusion Technology

When the eely hagfish senses danger, it spews out a cloud of milky slime that blinds and gags potential predators. The DOD’s version of that secretes its own mucous gunk—one idea is to affix the contraption to autonomous watercraft—fine-tuned to ensnare the propellers of enemy ships and submarines. Now the agency is looking at whether spider’s silk could fortify a next-gen recipe.

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