The recent use of armed, unmanned drones in Afghanistan and Yemen has shown that America's armed forces have become good at applying new weapons technology in the field. [Electromagnetic] weapons are able to destroy electronic systems and temporarily incapacitate people, all without the mess of explosions and gunfire. Using different types of electromagnetic energy (the same stuff as radio waves, X-rays and light) ... they could disrupt a variety of enemy systems, from missile targeting and launch electronics, to command-and-control systems. So-called "active denial" technology (which earns its moniker by actively herding people out of its path) works by using a beam of millimetre-length microwaves to heat up a person's skin. The marines are planning to put a version of the weapon on to a jeep. Range and properties are classified, but military newspapers say it can heat a person's skin to 55°C (130°F) at distances of up to 750 metres. David Fidler, a law professor at Indiana University, says that, because these weapons are most likely to be used on civilians, it is not clear that using them is legal under the international rules governing armed conflict. Steve Goose of Human Rights Watch ... says that too much secrecy still surrounds them. Weapons such as the active denial system could cause severe trauma, or even death, if fired at close range or held on a target for too long. Is it acceptable to shoot or bomb somebody if you have the option only to disable them?