Orbital bombardment

The cold war

The Soviet Union has had a Fractional Orbital Bombardment System deployed from 1968-1983.

The SALT II treaty (1979) prohibited the deployment of orbital weapons of mass destruction:
: Each Party undertakes not to develop, test, or deploy:
:(...)
:(c) systems for placing into Earth orbit nuclear weapons or any other kind of weapons of mass destruction, including fractional orbital missiles;''

The missile was phased out in January 1983 in compliance with this treaty.

Orbital bombardment systems with conventional warheads may be allowed, but do not seem very efficient.

Science fiction

Orbital bombardment systems occasionally feature in speculation and science fiction, and are in fact better known than their real-world counterpart. Typically, the assault is conducted by spacecraft as a part of interplanetary rather than intraplanetary warfare. The level of technology used in such a feat would be far beyond our current one.

An effective orbital bombardment is regarded as one of the most devastating forms of attack, though the concept is not a problemless one. The presence of an atmosphere may serve to burn up projectiles and disperse beam weapons. Planetary shielding is the most obvious countermeasure and may prohibit attacks entirely.

The greatest advantages are the accessibility of targets and the difficulty of returning fire. Surface-to-space weaponry has to deal with the gravity well, not to mention that it's usually very easy to spot and destroy even before firing. An unthreatened bombardment can continue until the attackers run out of ammunition.

Worse, those capable of such a feat are also more than likely to possess nuclear weapons at the least. Numerous planet killers operate using this method.

Mass drivers have been presented in several works as being particularly well-suited to the task.