Was the Soviet invasion of Afghanistan one of the major reasons that led to the fall of Soviet Union?
That is what the world history teacher told me.
Please show your sources.
The Review Article, Antony Kalashnikov (2012) "Differing Interpretations: Causes of the Collapse of the Soviet Union" Constellations:
"there is a correlation between mediums of writing and the "factor of collapse" they tend to espouse."
"that the historiography is best classified by "factors for collapse", and that these are: economic, nationalities, political, and systemic. It is interesting to note that while most studies (textbooks being the notable exception) tend to opt for one factor as being most important in bringing about collapse, they don't argue it vis-à-vis others. On the contrary, they do not engage other standpoints,"
Afghanistan is mentioned once in this review article, and only as part of the "briefing" of the context of the time.
Therefore—no substantive historiography of the collapse of the Soviet Union ascribes Afghanistan as a cause.
Therefore—Afghanistan was not one of the major reasons that led to the fall of Soviet Union.
Yes, the soviet defeat in Afghanistan was a major contributor to the fall of the Soviet Union. The Red Army was the institutional guarantee of the Soviet Unions stability; it brought together draftees from all of the member republics into a single organization under Russian domination which could be used to control those same republics and could be used to prop up the Warsaw pact allies.
Imagine if the United States was a one party state where the integrity of the federal whole was dependent on our militaries ability to keep separatist forces in each state under control. Then posit that our once vaunted military is forced to undergo a humiliating withdraw, as in Vietnam. What would this do to the stability of our hypothetical US dictatorship in a time of economic crisis?
To quote one source:
(1) Perception effects: it changed the perceptions of leaders about the efficacy of using the military to hold the empire together and to intervene in foreign countries
(2) Military effects: it discredited the Red Army, created cleavage between the party and the military, and demonstrated that the Red Army was not invincible, which emboldened the non Russian republics to push for independence;
(3) Legitimacy effects: it provided non-Russians with a common cause to demand independence since they viewed this war as a Russian war fought by non Russians against Afghans
(4) Participation effects: it created new forms of political participation, started to transform the press/media before glasnost, initiated the first shots of glasnost, and created a significant mass of war veterans (Afghansti) who formed new civil organizations weakening the political hegemony of the communist party
Obviously, there were many different factors that contributed to the fall of the USSR, with stagnating economic growth perhaps the most critical, but the Afghan war weakened the resolve and cohesion of the Soviet government and strengthened the resolve of dissidents in the USSR and it's Warsaw Pact allies, precisely in the time when the USSR could least afford it economically. No longer having full confidence in the Red Army, the Soviet government under Gorbachev abandoned military intervention as a tool to prop up its satellite states, making bloodless revolutions more likely (see my answer here). Once nationalist revolutions started externally, the effect cascaded internally, where the Afghan War had contributed to internal dissent; the resulting wave of dissent and demands for independence destroyed the Soviet Union itself.