ended. "70 Years of Gidroproekt and Hydroelectric Power in Russia". Unification of republics On 28 December 1922, a conference of plenipotentiary delegations from the Russian sfsr, the Transcaucasian sfsr, the Ukrainian SSR and the Byelorussian SSR approved the Treaty on the Creation of the ussr 30 and the Declaration of the Creation of the ussr. The Central Committee in turn voted for a Politburo (called the Presidium between 19521966 Secretariat and the General Secretary (First Secretary from 1953 to 1966 the de facto highest office in the Soviet Union. In 1968, the Soviet Union and Warsaw Pact allies invaded Czechoslovakia to halt the Prague Spring reforms. The authors attribute this poor performance to low productivity of capital in the Soviet Union. 41 Historian and archival researcher Stephen.