Railguns can deliver at this time a 25 pound projectile and readily exceed 3 km/s. The Navy began working on the railgun a decade ago and has spent more than half a billion dollars. They developed the railgun as a potent offensive weapon to blow holes in enemy ships, destroy tanks and level terrorist camps. It will also knock enemy missiles out of the sky more inexpensively and in greater numbers than current missile-defense systems.
The basic idea was to conceive a set of railguns that would be inexpensive but would have enormous deterrent value. A railgun requires a power plant that generates 25 megawatts, enough electricity to power 18,750 homes. Currently the only US Navy ships that can produce enough electrical power to get desired performance are the Zumwalt-class destroyers which can generate 78 megawatts of power, more than is necessary to power a railgun. The railgun faces many technical barriers before it is battle ready.