Sino-Soviet split in the context of "Sino-Soviet border conflict"

The Cold War was a period of global geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which began in the aftermath of the Second World War and ended with the dissolution of the Soviet Union in 1991. The term cold war is used because there was no direct fighting between the two superpowers, though each supported opposing sides in regional conflicts known as proxy wars. In addition to the struggle for ideological and economic influence and an arms race in both conventional and nuclear weapons, the Cold War was expressed through technological rivalries such as the Space Race, espionage, propaganda campaigns, embargoes, and sports diplomacy.

After the end of the Second World War in 1945, during which the US and USSR had been allies, the USSR installed satellite governments in its occupied territories in Eastern Europe and North Korea by 1949, resulting in the political division of Europe (and Germany) by an "Iron Curtain". The USSR tested its first nuclear weapon in 1949, four years after their use by the US on Hiroshima and Nagasaki, and allied with the People's Republic of China, founded in 1949. The US declared the Truman Doctrine of "containment" of communism in 1947, launched the Marshall Plan in 1948 to assist Western Europe's economic recovery, and founded the NATO military alliance in 1949 (matched by the Soviet-led Warsaw Pact in 1955). The Berlin Blockade of 1948 to 1949 was an early confrontation, as was the Korean War of 1950 to 1953, which ended in a stalemate.

The Cuban Missile Crisis, also known as the October Crisis (Spanish: Crisis de Octubre) in Cuba, or the Caribbean Crisis (Russian: Карибский кризис, romanized: Karibskiy krizis), was a 13-day confrontation between the governments of the United States and the Soviet Union, when American deployments of nuclear missiles in the United Kingdom, Italy and Turkey were matched by Soviet deployments of nuclear missiles in Cuba. The crisis lasted from 16 to 28 October 1962. The confrontation is widely considered the closest the Cold War came to escalating into full-scale nuclear war.

From 1959, the US government based Thor nuclear missiles in England, known as Project Emily. In 1961, the US put Jupiter nuclear missiles in Italy and Turkey. All were within range of Moscow. The US had trained a paramilitary force of Cuban expatriates, which the CIA led in an attempt to invade Cuba and overthrow its government. Starting in November of that year, the US government engaged in a violent campaign of terrorism and sabotage in Cuba, referred to as the Cuban Project, which continued throughout the first half of the 1960s. The Soviet administration was concerned about a Cuban drift towards China, with which the Soviets had an increasingly fractious relationship. In response to these factors the Soviet and Cuban governments agreed, at a meeting between leaders Nikita Khrushchev and Fidel Castro in July 1962, to place nuclear missiles on Cuba to deter a future US invasion. Construction of launch facilities started shortly thereafter.

The Second World was one of the "Three Worlds" formed by the global political landscape of the Cold War, as it grouped together those countries that were aligned with the Eastern Bloc of the Soviet Union and allies in Warsaw Pact. This grouping was directly opposed to the First World, which similarly grouped together those countries that were aligned with the Western Bloc of the United States and allies in NATO. It included communist states that were originally under the Soviet sphere of influence, though some eventually broke away from the Soviet ideology (e.g., Yugoslavia's split and China's split) to develop their own path as socialist states while retaining their communist governments. Most communist states remained under Soviet influence until the Revolutions of 1989. In 1991, upon the dissolution of the Soviet Union, only five communist states remained: China, Cuba, Laos, North Korea, and Vietnam. Though the terms "First World" and "Third World" continue to see present-day relevance in colloquial speech, albeit with a repurposed definition, the term "Second World" is obsolete outside of a Cold War context.

The People's Republic of China emerged as a great power and one of the three big players in the tri-polar geopolitics (PRC-US-USSR) during the Cold War, after the Korean War in 1950–1953 and the Sino-Soviet split in the 1960s, with its status as a recognized nuclear weapons state. Currently, China has one of the world's largest populations, second largest GDP (nominal) and the largest economy in the world by PPP.

In 1950–1953 it fought an undeclared war in Korea against the United States. Until the late 1950s it was allied with the Soviet Union but by 1960 they began a bitter contest for control over the local communist movement in many countries. It reached détente with the United States in 1972. After Chinese Communist Party chairman Mao Zedong died in 1976, Deng Xiaoping led a massive process of industrialization and emphasized trade relations with the world, while maintaining a low key, less ideological foreign policy, widely described by the phrase Taoguang Yanghui, or "hide one's talent and bide one's time". The Chinese economy grew very rapidly giving it steadily increasing power and ambition.

The term "Soviet empire" collectively refers to the world's territories that the Soviet Union dominated politically, economically, and militarily. This phenomenon, particularly in the context of the Cold War, is used by Sovietologists to describe the extent of the Soviet Union's hegemony over the Second World.

The Cambodian–Vietnamese War was an armed conflict from 1978 to 1989 between the Khmer Rouge and Vietnam, and their respective allies. It began in December 1978, with a Vietnamese invasion of Cambodia which toppled the Khmer Rouge and ended in 1989 with the withdrawal of Vietnamese forces from Cambodia. This Cold War conflict was part of the Third Indochina War and Sino-Soviet split with the Soviet Union supporting Vietnam and China supporting the Khmer Rouge.

Despite both being communist, the alliance between the Communist Party of Vietnam and the Khmer Rouge broke down after both defeated Vietnamese and Cambodian anti-communist regimes respectively in the Vietnam War. As a result, the war was preceded by years of conflict between Vietnam and the Khmer Rouge, led by Pol Pot, when the Khmer Rouge ruled Democratic Kampuchea repeatedly invaded Vietnam, including massacres by the Khmer Rouge, notably the Ba Chúc massacre of over 3,000 Vietnamese civilians in April 1978. On 21 December 1978, the Vietnamese launched a limited offensive towards the town of Kratie. On 23 December 1978, 10 out of 19 divisions of the Khmer Rouge's Kampuchea Revolutionary Army opened fire along the border with Vietnam with the goal of invading the southwestern border provinces of Đồng Tháp, An Giang and Kiên Giang. On 25 December 1978, Vietnam supported Cambodian dissidents in exile and launched a full-scale invasion of Kampuchea, occupying the country in two weeks, capturing the capital Phnom Penh, and removing the Khmer Rouge government of the Communist Party of Kampuchea from power. In doing so, Vietnam put an ultimate stop to the Cambodian genocide which had killed between 1.2 and 2.8 million people or between 13 and 30 percent of the country's population since 1975. However, the Khmer Rouge regime maintained its membership in the United Nations and the war isolated Vietnam from the international community except the Eastern Bloc. The Vietnamese occupation caused discontent among Cambodians.

The Albanian–Soviet split (Russian: Албано-советский раскол, romanized: Albano-sovetskiy raskol; Albanian: Ndarja shqiptaro-sovjetike) was the gradual worsening of relations between the Union of Soviet Socialist Republics (USSR) and the People's Republic of Albania, which occurred in the 1956–1961 period as a result of Soviet leader Nikita Khrushchev's rapprochement with Yugoslavia along with his "Secret Speech" and subsequent de-Stalinization, including efforts to extend these policies into Albania as was occurring in other Eastern Bloc states at the time.

However, the Albanian–Soviet split did not become public until 1960, when, during the Bucharest Conference of Representatives of Communist and Workers Parties, the Albanian delegation, led by Hysni Kapo, did not support Khrushchev's ideological views on the Sino-Soviet split.

Nuclear proliferation is the spread of nuclear weapons to additional countries, particularly those not recognized as nuclear-weapon states by the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT. Nuclear proliferation occurs through the spread of fissile material, and the technology and capabilities needed to produce it and to design and manufacture nuclear weapons. In a modern context, it also includes the spread of nuclear weapons to non-state actors. Proliferation has been opposed by many nations with and without nuclear weapons, as governments fear that more countries with nuclear weapons will increase the possibility of nuclear warfare (including the so-called countervalue targeting of civilians), de-stabilize international relations, or infringe upon the principle of state sovereignty. Conversely, supporters of deterrence theory argue that controlled proliferation decreases conflict rates via nuclear peace.

Nuclear weapons were initially researched during World War II, jointly by the United States, United Kingdom and Canada, and separately by Germany, Japan, the Soviet Union, and France. The United States was the first and is the only country to have used a nuclear weapon in war, when it used two bombs against Japan in August 1945. After surrendering, Germany and Japan ceased to be involved in any nuclear weapon research. A nuclear arms race followed, with further countries developing and testing nuclear weapons. The US primarily competed with the Soviet Union, which carried out their first test in 1949. Seven other countries developed nuclear weapons during the Cold War. The UK and France, both NATO members, developed fission and fusion weapons throughout the 1950s, and 1960s, respectively. China developed both against the backdrop of the Sino-Soviet split.