For several years, up until 2003, the U.S. Navy mentioned electromagnetic armor, or DAPS (Dynamic Armor Protection System) being developed for the planned CVN-21 class of carriers. The basic technology behind DAPS was not complex. Areas above the waterline would have two layers of thin armor, separated by a small air space. The two layers of armor would be electrified, and when the armor was hit by a shaped charge (favored for cruise missile warheads) the jet of superhot plasma, formed by the shaped charge warhead going off, would be broken up by the electromagnetic field formed when the two layers of armor were forced together. The big problem with DAPS was the huge amount of electricity required when the system was turned on. However, in the next decade or so, warship power plants are expected catch up with the needs of DAPS systems.
DAPS is also being developed for armored vehicles, and enough power can be generated by these vehicles to support a system that protects against small shaped charges, such as an RPG, or other small rocket. More power, than current vehicles generate, would be needed to protect against the larger shaped charge warheads of ATGMs (anti-tank guided missiles.)