Union of Soviet Socialist Republics in the context of "Soviet of Nationalities"

In the Soviet Union, a Union Republic (Russian: Сою́зная Респу́блика, romanized: Soyúznaya Respúblika) or unofficially a Republic of the USSR was a constituent federated political entity with a system of government called a Soviet republic, which was officially defined in the 1977 constitution as "a sovereign Soviet socialist state which has united with the other Soviet republics to form the Union of Soviet Socialist Republics" and whose sovereignty is limited by membership in the Union. As a result of its status as a sovereign state, the Union Republic de jure had the right to enter into relations with foreign states, conclude treaties with them and exchange diplomatic and consular representatives and participate in the activities of international organizations (including membership in international organizations). The Union Republics were perceived as national-based administrative units of the Union of Soviet Socialist Republics (USSR).

The Soviet Union was formed in 1922 by a treaty between the Soviet republics of Byelorussia, Russian SFSR (RSFSR), Transcaucasian Federation, and Ukraine, by which they became its constituent republics of the Union of Soviet Socialist Republics (Soviet Union). For most of its history, the USSR was a one-party state led by the Communist Party of the Soviet Union. Key functions of the USSR were highly centralized in Moscow until its final years, despite its nominal structure as a federation of republics; the light decentralization reforms during the era of perestroika (reconstruction) and glasnost (voice-ness, as in freedom of speech) conducted by Mikhail Gorbachev as part of the Helsinki Accords are cited as one of the factors which led to the dissolution of the USSR in 1991 as a result of the Cold War and the creation of the Commonwealth of Independent States.

The Autonomous Republic of Crimea is a de jure administrative division of Ukraine encompassing most of Crimea that was unilaterally annexed by Russia in 2014. The Autonomous Republic of Crimea occupies most of the peninsula, while the City of Sevastopol (a city with special status within Ukraine) occupies the rest.

The Cimmerians, Scythians, Greeks, Goths, Huns, Bulgars, Khazars, Byzantine Greeks, the state of Kievan Rus', Kipchaks, Italians, and Golden Horde Mongols and Tatars each controlled Crimea in its earlier history. In the 13th century, it was partly controlled by the Venetians and by the Genoese, and in the late 15th century, it was partly under Polish suzerainty. They were followed by the Crimean Khanate and the Ottoman Empire in the 15th to 18th centuries, the Russian Empire in the 18th to 20th centuries, Germany during World War II, and the Russian Soviet Federative Socialist Republic, and later the Ukrainian Soviet Socialist Republic, within the Soviet Union during the rest of the 20th century until Crimea became part of independent Ukraine with the breakup of the Soviet Union in 1991.

Marxism–Leninism (Russian: марксизм-ленинизм, romanized: marksizm-leninizm) is a communist ideology that became the largest faction of the communist movement in the world in the years following the October Revolution. It was the predominant ideology of most communist governments throughout the 20th century. It was developed in the Union of Soviet Socialist Republics by Joseph Stalin and drew on elements of Bolshevism, Leninism, and Marxism. It was the state ideology of the Soviet Union, Soviet satellite states in the Eastern Bloc, and various countries in the Non-Aligned Movement and Third World during the Cold War, as well as the Communist International after Bolshevization.

Today, Marxism–Leninism is the de jure ideology of the ruling parties of China, Cuba, Laos, and Vietnam, as well as many other communist parties. The state ideology of North Korea is derived from Marxism–Leninism, although its evolution is disputed.

The Premier of the Soviet Union (Russian: Глава Правительства СССР) was the head of government of the Union of Soviet Socialist Republics (USSR). From 1923 to 1946, the name of the office was Chairman of the Council of People's Commissars, and from 1946 to 1991 its name was Chairman of the Council of Ministers. During the dissolution of the Soviet Union in 1991, its name was briefly Prime Minister and later Chairman of the Committee on the Operational Management of the Soviet Economy. The first Soviet premier was the country's founder and first leader, Vladimir Lenin. After General Secretary of the Communist Party Joseph Stalin rose to power in 1924, the de facto leader of the Soviet Union typically was the party's General Secretary, with Stalin and his successor Nikita Khrushchev also serving as premier. Twelve individuals held the post.

The Presidium of the Supreme Soviet (Russian: Президиум Верховного Совета, romanized: Prezidium Verkhovnogo Soveta) was the standing organ of the highest body of state authority in the Union of Soviet Socialist Republics (USSR). The presidium was elected by joint session of both houses of the Supreme Soviet to act on its behalf while the Supreme Soviet was not in session. By the 1936 and 1977 Soviet Constitution, the Presidium of the Supreme Soviet served as the collective head of state of the USSR. In all its activities, the Presidium was accountable to the Supreme Soviet of the USSR.

Beside the all-Union body they were also in all union republics (e.g.: Presidium of the Supreme Soviet of the Russian SFSR, Presidium of the Ukrainian SSR, etc.) and other regions including autonomous republics. Structure and functions of the presidiums in these republics were virtually identical.

In the Union of Soviet Socialist Republics (USSR), national delimitation was the process of specifying well-defined national territorial units (Soviet socialist republics [SSR], autonomous Soviet socialist republics [ASSR], autonomous oblasts [provinces], raions [districts] and okrugs [circuits]) from the ethnic diversity of the USSR and its subregions.

The Russian-language term for this Soviet state policy was razmezhevanie (Russian: национально-территориальное размежевание, natsionalno-territorialnoye razmezhevaniye), which is variously translated in English-language literature as "national-territorial delimitation" (NTD), "demarcation", or "partition". National delimitation formed part of a broader process of changes in administrative-territorial division, which also changed the boundaries of territorial units, but was not necessarily linked to national or ethnic considerations.