A rocket is a self-propelled, unguided weapon system powered by a rocket motor. Rockets are used primarily as medium and long-range artillery systems, although historically they have also seen considerable use as air-to-ground, some use as air-to-air weapons, and even a few examples of surface-to-air devices. Examples of modern surface-to-surface rocket systems include the BM-27 Uragan and M270 Multiple Launch Rocket System.