[8] After the liberation of the Karelo-Finnish Soviet Socialist Republic in 1944, a few members of the command of the Karelian Front (including General Terenty Shytkov) proposed to deport the indigenous population of the Karelo-Finnish SSR to Siberia and the Kazakh SSR and liquidate the republic.

[9] He joined the All-Union Communist Party (Bolsheviks) in 1926,[10] but worked as a social science teacher at Solgalich Secondary School from 1927 to 1929.

He became the Head of the Department of Public Education of the Solgalich District Executive Committee in 1929 and remained in the position until 1931.

He served as the Head of the Department of Propaganda and Agitation of the Solgalich District Committee of the Communist Party from 1931 to 1932.

[11] After returning from university in 1935, Kupriyanov served as the Head of the School Department of the Dzerzhinsky District Committee of the Communist Party.

He served as the First Secretary of the Kuybyshevsky District Committee of the Communist Party of the Soviet Union from 1937 to 1938 in Leningrad.

[6] Kupriyanov was elected as the First Secretary of the Karelian Regional Committee of the Communist Party in June 1938 on the recommendation of Andrei Zhdanov to Stalin.

Kupriyanov soon became involved in the Leningrad Affair, he was accused of "failure to fulfill plans in industry and agriculture, patronage of workers who had compromised themselves, clampdown and lack of collegiality in work" by the Central Committee of the Communist Party of the Karelo-Finnish SSR.

On January 17, 1952, the Military Collegium of the Supreme Court of the USSR sentenced Kupriyanov to 25 years of forced labor with confiscation of all property under Article 58.

[20] He was rehabilitated on July 31, 1957, which reinstated his Communist Party membership, his military rank of Major general, and his awards.