Ballistic missiles are powered by rockets initially but then follow an unpowered, parabolic, free-falling trajectory toward their targets. They are classified by the maximum distance that they can travel, which is a function of how powerful the missile’s engines (rockets) are and the weight of the missile’s payload, or warhead. To add more distance to a missile’s range, rockets are stacked on top of each other in a configuration referred to as staging.
There are four general classifications of ballistic missiles:
Short-range ballistic missiles, traveling less than 1,000 kilometers (approximately 620 miles);
Medium-range ballistic missiles, traveling between 1,000–3,000 kilometers (approximately 620-1,860 miles);
Intermediate-range ballistic missiles, traveling between 3,000–5,500 kilometers (approximately 1,860-3,410 miles);
Intercontinental ballistic missiles (ICBMs), traveling more than 5,500 kilometers.
Unlike ballistic missiles, cruise missiles remain within the atmosphere for the duration of their flight. Cruise missiles are propelled by jet engines and can be launched from land-, air-, or sea-based platforms. Due to their constant propellants, they are more maneuverable than ballistic missiles, though they are also slower than their ballistic counterparts.
A hypersonic boost-glide vehicle (HGV) is fired by rockets into space and then released to fly to its target along the upper atmosphere. Unlike ballistic missiles, a boost-glide vehicle flies at a lower altitude and can change its intended target and trajectory repeatedly during its flight. The second type, a hypersonic cruise missile, is powered through its entire flight by advanced rockets or high-speed jet engines. It is a faster version of existing cruise missiles.