As a solid-fuel rocket, this could be fired at short notice from mobile launchers.

ECONOMIST: Nuclear proliferation

As a result, real concerns are beginning to be expressed about the viability of the U.S. industrial base for solid-fuel rocket motors.

CENTERFORSECURITYPOLICY: Farewell to space

The term hybrid is used because this type of rocket motor uses neither all-liquid fuel nor all-solid fuel, but a combination of both.

BBC: Hybrid success for British rocket