The last Soviet government on the 1968 invasion of Czechoslovakia

One of the events being recalled in the multiples-of-10-years retrospectives is the invasion of Czechoslovakia i 1968.

the one-paragraph description of the event from the reliably stodgy Encyclopedia Britannica, Prague Spring 03/07/2018:

Prague Spring, brief period of liberalization in Czechoslovakia under Alexander Dubček in 1968. Soon after he became first secretary of the Czechoslovak Communist Party on January 5, 1968, Dubček granted the press greater freedom of expression; he also rehabilitated victims of political purges during the Joseph Stalin era. In April he promulgated a sweeping reform program that included autonomy for Slovakia, a revised constitution to guarantee civil rights and liberties, and plans for the democratization of the government. Dubček claimed that he was offering “socialism with a human face.” By June many Czechs were calling for more rapid progress toward real democracy. Although Dubček insisted that he could control the country’s transformation, the Soviet Union and other Warsaw Pact countries viewed the developments as tantamount to counterrevolution. On the evening of August 20, Soviet armed forces invaded the country and quickly occupied it. As hard-line communists retook positions of power, the reforms were curtailed, and Dubček was deposed the following April.

I just came across this item, "Warschauer Vertrag und sowjetische Regierung verurteilen CSSR-Intervention 1968" Blätter für deutsch und internationale Politik 1990-01:

Wir stimmen der Meinung des Präsidiums des ZK der KPTsch und der Regierung der CSSR zu, wonach der Einmarsch der Armeen von fünf sozialistischen Ländern in die Tschechoslowakei im Jahre 1968 unberechtigt und der entsprechende Beschluß im Lichte aller jetzt bekannten Fakten ein Fehler war.

My translation.

We agree with the opinion [Central Committee] and [The Czechoslovakian Communist Party], according which which the entries of the armies of five socialist countries into Czechoslovakia in the year 1968 was unjustified and the decision, in light of all the currently known facts, was a mistake.