The Outer Space Treaty, formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a multilateral treaty that forms the basis of international space law. Negotiated and drafted under the auspices of the United Nations, it was opened for signature in the United States, the United Kingdom, and the Soviet Union on 27 January 1967, entering into force on 10 October 1967. As of February 2021, 111 countries are parties to the treatyincluding all major spacefaring nationsand another 23 are signatories.The Outer Space Treaty was spurred by the development of intercontinental ballistic missiles (ICBMs) in the 1950s, which could reach targets through outer space. The Soviet Union's launch of Sputnik, the first artificial satellite, in October 1957, followed by a subsequent arms race with the United States, hastened proposals to prohibit the use of outer space for military purposes. On 17 October 1963, the U.N. General Assembly unanimously adopted a resolution prohibiting the introduction of weapons of mass destruction in outer space. Various proposals for an arms control treaty governing outer space were debated during a General Assembly session in December 1966, culminating in the drafting and adoption of the Outer Space Treaty the following January.Key provisions of the Outer Space Treaty include prohibiting nuclear weapons in space; limiting the use of the Moon and all other celestial bodies to peaceful purposes; establishing that space shall be freely explored and used by all nations; and precluding any country from claiming sovereignty over outer space or any celestial body. Although it forbids establishing military bases, testing weapons and conducting military maneuvers on celestial bodies, the treaty does not expressly ban all military activities in space, nor the establishment of military space forces or the placement of conventional weapons in space.

From 1968 to 1984, the OST birthed four additional agreements: rules for activities on the Moon; liability for damages caused by spacecraft; the safe return of fallen astronauts; and the registration of space vehicles.OST provided many practical uses and was the most important link in the chain of international legal arrangements for space from the late 1950s to the mid-1980s. OST was at the heart of a 'network' of inter-state treaties and strategic power negotiations to achieve the best available conditions for nuclear weapons world security. The OST also declares that space is an area for free use and exploration by all and "shall be the province of all mankind". Drawing heavily from the Antarctic Treaty of 1961, the Outer Space Treaty likewise focuses on regulating certain activities and preventing unrestricted competition that could lead to conflict. Consequently, it is largely silent or ambiguous on newly developed space activities such as lunar and asteroid mining. Nevertheless, the Outer Space Treaty is the first and most foundational legal instrument of space law, and its broader principles of promoting the civil and peaceful use of space continue to underpin multilateral initiatives in space, such as the International Space Station and the Artemis Program.

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a communist state that spanned Eurasia from 1922 to 1991. It was nominally a federal union of multiple national republics; in practice its government and economy were highly centralized until its final years. The country was a one-party state (prior to 1990) governed by the Communist Party of the Soviet Union, with Moscow as its capital within its largest and most populous republic, the Russian SFSR. Other major urban centers were Leningrad (Russian SFSR), Kiev (Ukrainian SSR), Minsk (Byelorussian SSR), Tashkent (Uzbek SSR), Alma-Ata (Kazakh SSR) and Novosibirsk (Russian SFSR). It was the largest country in the world, covering over 22,402,200 square kilometres (8,649,500 sq mi), and spanning eleven time zones.

The Soviet Union had its roots in the October Revolution of 1917 when the Bolsheviks, headed by Vladimir Lenin, overthrew the Provisional Government that had earlier replaced the house of Romanov of the Russian Empire. They established the Russian Soviet Republic, the world's first constitutionally guaranteed socialist state. Tensions escalated into a civil war between the Bolshevik Red Army and many anti-Bolshevik forces across the former Empire, among whom the largest faction was the White Guard. The White Guard engaged in violent anti-communist repression against the Bolsheviks and suspected worker and peasant Bolsheviks known as the White Terror. The Red Army expanded and helped local Bolsheviks take power, establishing soviets, repressing their political opponents and rebellious peasants through Red Terror. By 1922, the balance of power had shifted and the Bolsheviks had emerged victorious, forming the Soviet Union with the unification of the Russian, Transcaucasian, Ukrainian and Byelorussian republics. Upon the conclusion of the civil war Lenin's government introduced the New Economic Policy, which led to a partial return of a free market and private property; this resulted in a period of economic recovery.

Following Lenin's death in 1924, Joseph Stalin came to power. Stalin suppressed all political opposition to his rule inside the Communist Party and inaugurated a command economy. As a result, the country underwent a period of rapid industrialization and forced collectivization, which led to significant economic growth, but also led to a man-made famine in 1932–1933. The Gulag labour camp system was also expanded in this period. Stalin also fomented political paranoia and conducted the Great Purge to remove his actual and perceived opponents from the Party through mass arrests of military leaders, Communist Party members, and ordinary citizens alike, who were then sent to correctional labor camps or sentenced to death.

On 23 August 1939, after unsuccessful efforts to form an anti-fascist alliance with Western powers, the Soviets signed a non-aggression pact with Nazi Germany. After the start of World War II, the formally neutral Soviets invaded and annexed territories of several Eastern European states, including the eastern regions of Poland, Lithuania, Latvia and Estonia. In June 1941 the Germans invaded, opening the largest and bloodiest theater of war in history. Soviet war casualties accounted for the majority of Allied casualties of the conflict in the process of acquiring the upper hand over Axis forces at intense battles such as Stalingrad. Soviet forces eventually captured Berlin and won World War II in Europe on 9 May 1945. The territory overtaken by the Red Army became satellite states of the Eastern Bloc. The Cold War emerged in 1947, where the Eastern Bloc confronted the Western Bloc, which would unite in the North Atlantic Treaty Organization in 1949.

Following Stalin's death in 1953, a period known as de-Stalinization and the Khrushchev Thaw occurred under the leadership of Nikita Khrushchev. The country developed rapidly, as millions of peasants were moved into industrialized cities. The USSR took an early lead in the Space Race with the first ever satellite and the first human spaceflight and the first probe to land on another planet, Venus. In the 1970s, there was a brief détente of relations with the United States, but tensions resumed when the Soviet Union deployed troops in Afghanistan in 1979. The war drained economic resources and was matched by an escalation of American military aid to Mujahideen fighters.

In the mid-1980s, the last Soviet leader, Mikhail Gorbachev, sought to further reform and liberalize the economy through his policies of glasnost and perestroika. The goal was to preserve the Communist Party while reversing economic stagnation. The Cold War ended during his tenure and in 1989, Warsaw Pact countries in Central and Eastern Europe overthrew their respective Marxist-Leninist regimes. Strong nationalist and separatist movements broke out across the USSR. Gorbachev initiated a referendum—boycotted by Lithuania, Latvia, Estonia, Armenia, Georgia, and Moldova — which resulted in the majority of participating citizens voting in favor of preserving the Union as a renewed federation. In August 1991, a coup d'état was attempted by Communist Party hardliners. It failed, with Russian President Boris Yeltsin playing a high-profile role in facing down the coup. The main result was the banning of the Communist Party. The republics, led by Russia and Ukraine, declared independence. On 25 December 1991, Gorbachev resigned. All the republics emerged from the dissolution of the Soviet Union as independent post-Soviet states. The Russian Federation (formerly the Russian SFSR) assumed the Soviet Union's rights and obligations and is recognized as its continued legal personality in world affairs.

The Soviet Union produced many significant social and technological achievements and innovations regarding military power. It boasted the world's second-largest economy and the largest standing military in the world. The USSR was recognized as one of the five nuclear weapons states. It was a founding permanent member of the United Nations Security Council as well as a member of the OSCE, the WFTU and the leading member of the Council for Mutual Economic Assistance and the Warsaw Pact.

Before its dissolution, the USSR had maintained its status as a superpower, alongside the United States, for four decades after World War II. Sometimes also called "Soviet Empire", it exercised its hegemony in East-Central Europe and worldwide with military and economic strength, proxy conflicts and influence in developing countries and funding of scientific research, especially in space technology and weaponry.