NKVD

The '''People's Commissariat for Internal Affairs (, ), abbreviated as NKVD''' (; ), was the interior ministry and secret police of the Soviet Union from 1934 to 1946. The agency was formed to succeed the Joint State Political Directorate (OGPU) secret police organization, and thus had a monopoly on intelligence and state security functions. The NKVD is known for carrying out political repression and the Great Purge under Joseph Stalin, as well as counterintelligence and other operations on the Eastern Front of World War II. The head of the NKVD was Genrikh Yagoda from 1934 to 1936, Nikolai Yezhov from 1936 to 1938, Lavrentiy Beria from 1938 to 1946, and Sergei Kruglov in 1946.

First established in 1917 as the NKVD of the Russian SFSR, the ministry was tasked with regular police work and overseeing the country's prisons and labor camps. It was disbanded in 1930, and its functions dispersed among other agencies before being reinstated as a commissariat of the Soviet Union in 1934. During the Great Purge in 1936–1938, on Stalin's orders, the NKVD conducted mass arrests, imprisonment, torture, and executions of hundreds of thousands of Soviet citizens. The agency sent millions to the Gulag system of forced labor camps and, during World War II, carried out the mass deportations of hundreds of thousands of Poles, Balts, and Romanians, and millions of ethnic minorities from the Caucasus, to remote areas of the country, resulting in millions of deaths. Hundreds of thousands of NKVD personnel served in Internal Troops divisions in defensive battles alongside the Red Army, as well as in "blocking formations," preventing retreat. The agency was responsible for foreign assassinations, including that of Leon Trotsky.