Recently, Masers have been under development as a non-lethal weapons.

The Marine Corps (in coordination with the Air Force) has recently developed a portable maser with integrated technology that limits the intensity of the beam of microwaves being emitted. The emission goes right through clothes, but rapidly heats the water and ion containing tissue that makes up human flesh(not surprisingly, microwaves really are used in your microwave to accomplish a similar feat, but in a slightly different manner). With the carefully limited output of this device, it does not penetrate very deeply into the body (and thus does not do lethal damage to internal organs).

Although information about the use of this new technology was not intended to be released until April (2001) it was published in Marine Corps Times somewhat earlier. A tech writer for UPI (Kelly Hearn) also published an article on shortly after the resulting media scramle. In her write up, she provided several insights into the weapon and how it might be used, saying:

"Unlike the other three branches, the Marines often are in situations where there are lots of innocent bystanders, where they have to control an unruly mob," said John Pike, director of GlobalSecurity.org, a non-profit policy research firm in Alexandria, Va. "Tear gas and rubber bullets just have not been effective, so they've want something more lethal than those and less lethal than an M16. Whether they have found that here remains to be seen."
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Retired Major General William L. Nash, the former commanding general of the 1st Armored Division, told UPI the device will inevitably create a race to build counter weapons. "The good news is the weapon is non-lethal but the bad news is that for every weapon there is bound to be a counter weapon," he said. "I can imagine someone trying to develop a polymer based shield against this, for example."