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).

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 result of the Cold War and the creation of the Commonwealth of Independent States.

The decision to downgrade Karelia to an autonomous republic within the Russian SFSR was made unilaterally by the central government without consulting its population.

This allowed for two Soviet Republics, Ukraine and Byelorussia, (as well as the USSR as a whole) to join the United Nations General Assembly as founding members in 1945.

In accordance with provisions present in its Constitution (versions adopted in 1924, 1936 and 1977), each republic retained the right to secede from the USSR.

The de facto dominance of the Russian republic is the reason that various historians (for example, Dmitri Volkogonov and others) have asserted that the union was a unitary state in fact albeit not in law.

[19]: 71, 483 [20] In practice, the USSR was a highly centralised entity from its creation in 1922 until the mid-1980s when political forces unleashed by reforms undertaken by Mikhail Gorbachev resulted in the loosening of central control and its ultimate dissolution.

Along with the state administrative hierarchy, there existed a parallel structure of party organizations, which allowed the Politburo to exercise large amounts of control over the republics.

[29] Starting in the late 1980s, under the rule of Mikhail Gorbachev, the Soviet government undertook a program of political reforms (glasnost and perestroika) intended to liberalise and revitalise the Union.

Political liberalisation allowed the governments of the union republics to openly invoke the principles of democracy and nationalism to gain legitimacy.

In addition, the loosening of political restrictions led to fractures within the Communist Party which resulted in a reduced ability to govern the Union effectively.

The rise of nationalist and right-wing movements, notably led by Boris Yeltsin in Russia, in the previously homogeneous political system undermined the Union's foundations.

On 8 December 1991, the remaining leaders of the republics signed the Belavezha Accords which agreed that the USSR would be dissolved and replaced with a Commonwealth of Independent States.