Soviet Aggression produced the Carter Doctrine.
Background: In August 1968, the leaders of the USSR penned the famous "Brezhnev Doctrine," which sought to justify Soviet domination over its neighbors. It stated:
"...when internal and external forces that are hostile to socialism seek to reverse the development of any socialist country in the direction of restoring the capitalist system, when a threat to the cause of socialism in that country appears, and a threat to the security of the socialist community as a whole, that is no longer only a problem for the people of that country, but also a common problem, a matter of concern for all socialist countries.
It goes without saying that such an action as military aid to a fraternal country to put an end to a threat to the socialist system is an extraordinary, an enforced step, which can be sparked off only by direct actions on the part of the enemies of socialism inside the country and beyond its frontiers --actions creating a threat to the common interests of the socialist camp." (quoted in Pickles, p. 164)
In December 1979, the Red Army moved forward into Afghanistan in an effort to keep in power Communist forces beset by growing civil war there. The Brezhnev Doctrine was used to explain this aggression.
In January 1980, the US formally announced its response. President Carter enunciated the "Carter Doctrine," which stated that:
"An attempt by any outside force to gain control of the Persian Gulf region will be regarded as an assault on the vital interests of the United States of America, and such an assault will be repelled by any means necessary, including military force" (quoted in Levering: 167).
sources:
Ralph B. Levering, The Cold War, 1945-1987 second edition (Arlington Heights, IL: Harlan Davidson, 1988).
Dorothy Pickles, Democracy (Baltimore, MD: Penguin, 1970).