What I mean by this is that the Soviet Union was dissolved to some extent because of the dissidents recognized in the West.

Quotation from Wikipedia in English:
https://en.wikipedia.org/wiki/Dissident

>>A dissident is a person who actively challenges an established political or religious system, doctrine, belief, policy, or institution.[1] In a religious context, the word has been used since 18th century, and in the political sense since 1940, coinciding with the rise of totalitarian systems, especially the Soviet Union, Nazi Germany, and Saudi Arabia.[2] In the Western World there are historical examples of people who have been considered and have considered themselves dissidents, such as the Dutch philosopher Baruch Spinoza. In totalitarian regimes, dissidents are often incarcerated without explicit political accusations, or due to infringements of the very same laws they were disputing, or because they are supporting progressive rights such as the free speech right.<<

>>Soviet dissidents who criticized the state faced possible legal sanctions under the Soviet Criminal Code[12] and faced the choice of exile, the mental hospital, or the labor camp.[13] Anti-Soviet political behavior, in particular, being outspoken in opposition to the authorities, demonstrating for reform, writing books were defined in some persons as being simultaneously a criminal act (e.g., violation of Articles 70 or 190-1), a symptom (e.g., ”delusion of reformism”), and a diagnosis (e.g., ”sluggish schizophrenia”).[14]<<

Example of a few named outstanding dissidents in the Sovjet Union was Andrei Sakharov, Aleksandr Solzhenitsyn, Václav Havel, Lech Wałęsa. As I see it, Wałęsa, was the small stone in the way..

If somebody wants to see more names here is a link: https://en.wikipedia.org/wiki/Category:Soviet_dissidents

Suitable English proverbs:
https://www.proz.com/kudoz/swedish-to-english/poetry-literature/2847889-liten-tuva-stj%C3%A4lper-stora-lass.html

A small stone in the way overturns a great wain.
A small leak will sink a great ship.
Small tuft topples big load.
Little strokes fell great oaks.
The straw that broke the camel’s back.
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Vad jag vill säga med detta är att Sovjetunionen upplöstes till viss del på grund av de dissidenter som erkänts i västländerna.

Citat från Wikipedia på Svenska: https://sv.wikipedia.org/wiki/Dissident

>>En dissident är en person som aktivt motarbetar den rådande ordningen. Vanligen avser man en politisk dissident som, oftast med fredliga medel, sätter sig upp mot en totalitär regim.<<

>>Dissident är den som stannar kvar inom det kritiserade systemet eller etablissemanget, medan den som lämnar det kallas för flykting. Inom juridiken benämns en person som reserverar sig mot ett domstolsbeslut för dissident.
I Sovjetunionen var Andrej Sacharov och Aleksandr Solzjenitsyn exempel på dissidenter, och i Kina anses Wei Jingsheng vara den första dissidenten i modern tid. I Västvärlden betraktas exempelvis Noam Chomsky som ledande dissident.<<

https://sv.wikipedia.org/wiki/Stora_utrensningen

>>Omfattning
Enligt offentliggjorda sovjetiska arkiv anhöll NKVD 1 548 366 offer av vilka 681 692 blev skjutna. Historikern Michael Ellman anser att det totala antalet dödsfall orsakad av utrensningen borde ligga i intervallet 950 000 till 1,2 miljoner om man räknar med alla dödsfall.[19]<<

>>Det finns historiker som tror att arkivmaterialet underskattar dödsfallen. Robert Conquest uppskattar antalet avrättade till två och en halv gånger så många som 681 692. Han menar att KGB har mörklagt stora delar av sitt arbete.[20]<<

Som jag ser det var Lech Wałęsa till viss del tuvan som välte lasset.

Lämpligt ordspråk:
Liten tuva välter stort lass.