Korets–Landau leaflet

The Korets–Landau leaflet, authored by the Soviet physicists Moisey Korets  and Lev Landau in 1938, condemned the Soviet leader Joseph Stalin and the NKVD as the response to the Great Purge in the Soviet Union.

Stalin was accused for betrayal of the October Revolution and the sociopolitical work of his regime, especially the secret police NKVD, was compared with the ones organized by German Nazi leader Adolf Hitler and the Italian Fascism leader Benito Mussolini, who at this time made active political struggle against Communism in their countries and were both ideological and political enemies of the Soviet Union. In making the opposition against Stalinism, the leaflet had made use of purely socialist ideas. In particular, it had used as the title the communist ideological slogan "Workers of the world, unite" borrowed from The Communist Manifesto by Karl Marx and Friedrich Engels which laid the ideological foundations of Stalin's All-Union Communist Party (bolsheviks).

Creation of the leaflet was greatly motivated by the UPTI affair, which resulted in imprisonments and executions of a number of leading Soviet scientists. Its propagation was planned on the International Workers' Day 1 May 1938, but did not come into the effect because was discovered by the NKVD, which arrested the authors. The investigation showed that the leaflet was compiled by Korets and edited by Landau. Some historians have supposed that its creation was a result of the wide provocation action performed among the Jewish scientists by the NKVD. Korets pointed out that the Jewish poet Pavel Kogan was the NKVD's instigator for the leaflet. Together with Landau and Korets,the Soviet physicist Yuri Rumer was also arrested. Landau was released thanks to Pyotr Kapitsa's support, but both Korets and Rumer were imprisoned in Gulag labor camps.