Czech demonstrators hold flags atop an overturned truck as other Prague residents surround Soviet tanks in  Prague, August, 1968.

Editor’s Note: Daniel Kumermann is a former foreign affairs journalist, Czech Ambassador to Israel (1999-2003), Consul General in Los Angeles (2006-2011), and signatory of the Charter 77 human rights declaration. The opinions expressed in this commentary are his own. View more opinion at CNN.

Prague CNN  — 

In the early hours of an August day in 1968, I was awakened by the continuous thunder of heavy planes flying low overhead – we lived relatively close to Prague’s largest airport.

It was about 3:00 a.m., and a few hours later came the explanation. The radio, instead of the usual morning music, had only one topic – the Czech government’s announcement that we were being occupied by the armies of the Warsaw Pact and should not resist in any way.

Two hours later, in the city center I saw the real thing: hundreds of tanks rolling around the streets, many destroying parked cars where it was too narrow to pass. Tanks patrolled the main corners and were stationed in front of almost every institution. It was not only the first time that I saw a tank, but could touch it too. It was also the first time I heard a machine gun from very close, and saw the bullet trails just above my head.

All these frightening details – and many more – are still firmly imbedded in my mind, 53 years later. Like the city buzzing with various small acts of resistance. Almost every wall was plastered with some kind of anti-Russian or anti-Soviet slogan, and thousands of various leaflets and special editions of newspapers were distributed.

Despite the overwhelming mass of steel around us, we kept refusing to accept its reality. We still believed that we could somehow protect and preserve the process of democratization of our country known as the Prague Spring.

But ultimately the “truth of the tanks” prevailed and their message was clear: no liberalization, let alone democracy, in any part of the Soviet bloc as it could threaten the total subservience of people in the rest of the empire.

A Czech woman yells at soldiers sitting on tanks in the streets of Prague in August, 1968.

Indeed the Soviet justification for occupation of Czechoslovakia was found in the so-called Brezhnev Doctrine of “limited sovereignty,” which claimed that any threat to socialist rule in any state of the bloc was a threat to them all. Notwithstanding the fact that the alleged threat came from the Czech Communist Party itself.

I turned 17 a few days before that fateful day – August 21, 1968 – the very formative age when one may already hold strong views and opinions, but they are still being reshaped and instilled. Thus the rolling tanks only further persuaded me that the whole communist system, and its rule from Moscow, were inherently evil. My view was further strengthened by the ensuing material and moral decay of my country in all possible ways and manners. All under the ever-watchful eye of Moscow.

In practical terms, the regime based on Russian tanks prevented me from traveling and learning the world in my school years and eventually sent me to manual jobs (mostly window cleaning) for 13 long years. Still, I could consider myself lucky because I was only 38 when the regime finally fell and I managed to squeeze in two meaningful careers. I say that because there were many, too many unlucky ones who lost all of their productive years to the communist rule.

I am describing all this in such personal detail to make clearer what many from my generation, as well as uncountable others in my country – younger and older – feel when we hear about Russian tanks rolling around Ukraine cities and countryside. But even more so when we hear Putin summoning the ghost of Brezhnev’s doctrine, according to which Moscow is entitled to feel threatened by an independent neighbor who could show that life outside Putin’s rule is also possible – and God forbid might even be better.

We see the continuity of the inherent imperial thinking – which in our case in 1968 had the veil of communist ideology and its promise of a bright future. In the case of Ukraine today, it is driven by Russian nationalism and savior complex of the supposed great leader.

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    That is the really bleak message for us here in the Czech Republic and for our neighboring countries, which also used to be under Soviet rule. We can be sure that if Putin succeeds in his current adventure he is not going to stop there – and his gaze will be locked on us. The Ukrainians fighting back against the Russian onslaught do so not only for their own freedom, but for our freedom as well. And for that they deserve our unmitigated gratitude.