The Soviet-led Warsaw Pact was the only military alliance to attack itself after its tanks rolled into Prague in 1968 to crush a reform movement there.
Some heard eerie echoes of the so-called Prague spring of 1968 and the Soviet crushing of the Hungarian revolution in 1956 after the deployment of troops from the Russian-led Collective Security Treaty Organisation CSTO to Kazakhstan on Thursday.
Since its founding in 1999, the CSTO hasn't made any joint deployments. It has been called upon to deal with internal unrest in one of its member states.
The revolt inspired foreign-backed terrorists to justify his appeal, but the call to the CSTO shows that he no longer felt he could trust his own forces, according to Kassym-Jomart Tokayev, the president of Kazakhstan. When Tokayev asked for his request, the CSTO jumped into action in a matter of hours, and Russian paratroopers were already arriving in Kazakhstan on Thursday morning.
The general secretary of the CSTO told the RIA news agency that the overall peacekeeping force would number about 2,500 and could be strengthened if necessary.
Some in Moscow praised the decision to intervene. Maxim Suchkov, the director of the Institute for International Studies at MGIMO, dismissed comparisons with the Soviet-era Warsaw Pact interventions as propaganda and said a short mission could boost Russia's standing in the region.
Suchkov wrote on Twitter that the events in Kazakhstan represented a crisis in which Moscow can be instrumental and helpful.
The decision to intervene was almost certainly taken by Moscow, as the CSTO is an alliance, according to a definite similarity to the Warsaw Pact. It was cheered on by Belarusian spokesman Alexander Lukashenko, who was able to crush a huge revolution using his own domestic forces in 2020, but Vladimir Putin will have made the final call.
Putin may be hoping that a swift mission will restore order and leave Kazakhstan grateful and indebted to Moscow, but the operation comes with risks.
One of the former presidents Nursultan Nazarbayev's main achievements was avoiding the conflict between the Kazakh majority and ethnic Russian minority in the country because of the fact that the CSTO move is seen as a Russian intervention.
Kazan has pursued a multi-vector foreign policy for years, and its close relations with Moscow were offset by good relations with western nations. As news broke on Wednesday of Tokayev's request to the CSTO, the editor-in-chief of the state-owned television station RT, Margarita Simonyan, set out a wishlist of demands.
She wrote on Twitter that we should definitely help, but we need to lay down some conditions as well. These included making Russian a second state language and recognising Crimea as part of Russia.
It was a sign that some in Moscow view the CSTO alliance. If Tokayev succeeds in crushing the protests with Moscow's help, the Russians may expect favors in return.