The Soviets had a system that was based on putting warheads into a fractional orbit, rather than on a ballistic path - Fractional Orbital Bombardment System (FOBS).

http://en.wikipedia.org/wiki/Fractional_Orbital_Bombardment_...

I can't find any details, but most descriptions seem to imply that they needed to have a rocket engine on the warhead to come out of orbit (which is what I would expect).