The most outspoken protest against the aggression in Czechoslovakia was the sit-down demonstration which took place in Red Square at 12 noon on 25 August 1968. A letter from one of the participants in the demonstration, Natalya Gorbanevskaya, gives detailed information about this event:
“To the chief editors of Rude Pravo, Unita, the Morning Star, L’Humanite,
The Times [London], Le Monde, the Washington Post, Neue Zuricher Zeitung,
the New York Times, and any other paper which will publish this letter .
Novopeschanaya St. 13/3,
28 August 1968
“I ask you to print my letter about the demonstration in Red Square in Moscow on 25 August 1968, since I am the sole participant of that demonstration still at liberty.
“The following people took part in the demonstration: Konstantin Babitsky, a linguist; Larissa Bogoraz, a philologist; Vladimir Dremlyuga, a worker; Vadim Delone, a poet; Pavel Litvinov, a physicist; Victor Fainberg, a fine arts specialist; and Natalya Gorbanevskaya, a poet. At midday we sat on the parapet at Place of Proclamation [in front of St Basil’s Cathedral, ed.] and unrolled banners with the slogans  LONG LIVE FREE AND INDEPENDENT CZECHOSLOVAKIA (written in Czech), SHAME ON THE OCCUPIERS, HANDS OFF CZECHOSLOVAKIA, FOR YOUR FREEDOM AND OURS. Almost immediately a whistle blew and plainclothes KGB men rushed at us from all corners of the square. They were on duty in Red Square, waiting for the Czechoslovak delegation’s departure  from the Kremlin.
“They ran up shouting ‘They’re all Jews!’, ‘Beat the anti-Sovietists!’ We sat quietly and did not resist. They tore the banners from our hands. They beat Victor Fainberg in the face until he bled, and knocked his teeth out. They hit Pavel Litvinov about the face with a heavy bag, and they snatched away from me a Czechoslovak flag and smashed it. They shouted at us, ‘Disperse, you scum!’ But we remained sitting. After a few minutes cars arrived, and all were bundled into them except me. I was with my three-month-old son, and therefore they did not seize me straight away. I sat at the Place of Proclamation for about another ten minutes. In the car they beat me. Several people from the crowd which had gathered, ones who had expressed their sympathy with us, were arrested along with us, and released only late in the evening.
“During the night searches were made of all those held, on the charge of ‘group activities flagrantly violating public order’. One of us, Vadim Delone, had already been conditionally sentenced under this article earlier, for his part in the demonstration of 22 January 1967, on Pushkin Square . After the search I was released, probably because I had two children to look after. I am continually being summoned to give evidence. I refuse to give evidence on the organization and conduct of the demonstration, since it was a peaceful demonstration which did not disturb public order. But I did give evidence about the rough and illegal actions of the people who detained us: I am ready to testify to this before world public opinion.
“My comrades and I are happy that we were able to take part in this demonstration, that we were able, if only for a moment, to interrupt the torrent of barefaced lies  and the cowardly silence, to show that not all the citizens of our country are in agreement with the violence which is being used in the name of the Soviet people. We hope that the people of Czechoslovakia have learned, or will learn about this. And the belief that the Czechs and the Slovaks, when thinking about the Soviet people, will think not only of the occupiers, but also of us, gives us strength and courage.
A team of investigators of the Moscow City Procuracy is conducting the investigation into the demonstration. They are Akimova, Gnevkovskaya, Lopushenkov, Galakhov and Solovyov. Three of them worked on the investigation into the Pushkin Square demonstration of 22 January 1967. General supervision of the progress of the investigation is in the hands of the Moscow Procurator’s assistant, Fyodorov.
The participants in the demonstration have been charged under Article 190-3 of the Criminal Code, which specifies a sentence of up to three years for obstructing the flow of transport and the work of State institutions (?), and also under Article 190-1 which envisages conviction for the dissemination of information “which defames the Soviet political and social system” (three years).
It has been learned for certain that — as part of the pre-trial investigation — material of a purely personal nature is being collected and that untrue versions of events are being concocted, which provide opportunities for false and misleading interpretations. Meanwhile the people who committed sadistic and hooligan acts in the square, in particular the beating up of Fainberg and Litvinov, have had no measures taken against them.