Mitigation, or response, could take several forms, depending in part on the nature and magnitude of a given threat, once it has been detected and evaluated. One possible response would be evacuation of the impact zone, to minimize loss of life. A closely related response is preparation to minimize the resultant damage due to fires, tidal waves, earthquakes, acid rain, and other after-effects, and to provide medical care to the victims. These forms of response, though important, would be grossly inadequate when dealing with a truly massive threat such as those discussed previously. In the event of a massive strike from space, the resultant apocalyptic disasters would render such efforts as fruitless as rearranging the deck chairs while the Titanic sinks. The only meaningful response to a massive strike is some form of direct intervention. Direct intervention may entail deflection or destruction of the approaching space object to prevent or mitigate any impact with Earth. The means for achieving this fall partially within the realm of existing military capabilities, and partially within the ambit of technologies superficially similar to some proposed/experimental aspects of the Strategic Defense Initiative (SDI). Depending on the physical size and other attributes of the threatening object, a variety of countermeasures might be effective in diverting or destroying it. Earth-based nuclear devices such as Intercontinental Ballistic Missiles (ICBMs) or their submarine-launched counterparts might suffice. Non-nuclear options conceivably would work, including kinetic energy or laser systems such as were explored under SDI. Some of these may require space-basing to be effective, while others may work in an Earth-based mode.

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Kunich, John C. "Planetary Defense: The Legality of Global Survival." Air Force Law Review. Vol. 41 (1997): 119-160. [ 1 reference ] [ page 128 ]