a railgun can accelerate projectiles to 8500 kph for 1% of the price of a missile. only ICBM are faster, at 24k kph. rail guns have been a SF staple for a long time.
The Navy will fire its electromagnetic railgun from a joint high speed vessel in 2016 as part of a broader effort to develop the long-range, high-energy weapon.
Gregor J. Rothfuss 