Foreign interventions by the Soviet Union

Though not officially belligerent during the Korean War (1950–53), the Soviet Union played a significant, covert role in the conflict; it provided material and medical services, as well as Soviet pilots and aircraft, most notably MiG-15 fighter jets, to aid the North Korean-Chinese forces against the United Nations forces. The Soviets claimed 510 UN aircraft shot down in just the first year of the war and a total of 1,300 during the entire war while losing only 345 of their own.[18]

Soviet T-54 tanks in Budapest on 31 October

After Stalinist Hungarian dictator Mátyás Rákosi was replaced by Imre Nagy following Stalin's death[19][not in citation given] and Polish reformist Władysław Gomułka was able to enact some reformist requests,[20] large numbers of protesting Hungarians compiled a list of demands,[21] including free secret-ballot elections, independent tribunals, and inquiries into Stalin and Rákosi Hungarian activities. Under the orders of Soviet defense minister Georgy Zhukov, Soviet tanks entered Budapest.[22] Protester attacks at the Parliament forced the collapse of the Soviet-backed government.[23]

The new government that came to power during the revolution formally disbanded the Hungarian secret police, declared its intention to withdraw from the Warsaw Pact and pledged to re-establish free elections. The Soviet Politburo thereafter moved to crush the revolution with a large Soviet force invading Budapest and other regions of the country.[24]Approximately 200,000 Hungarians fled Hungary,[25] some 26,000 Hungarians were put on trial by the new Soviet-installed János Kádár government and, of those, 13,000 were imprisoned.[26] Imre Nagy was executed, along with Pál Maléter and Miklós Gimes, after secret trials in June 1958. By January 1957, the Hungarian government had suppressed all public opposition. These Hungarian government's violent oppressive actions alienated many Western Marxists, yet strengthened communist control in all the European communist states, cultivating the perception that communism was both irreversible and monolithic.

Czechoslovaks carry their national flag past a burning Soviet tank in Prague.

A period of political liberalization took place in 1968 in Eastern Bloc country Czechoslovakia called the Prague Spring. The event was spurred by several events, including economic reforms that addressed an early 1960s economic downturn.[27][28] In April, Czechoslovakian leader Alexander Dubček launched an "Action Program" of liberalizations, which included increasing freedom of the press, freedom of speech and freedom of movement, along with an economic emphasis on consumer goods, the possibility of a multiparty government and limiting the power of the secret police.[29][30] Initial reaction within the Eastern Bloc was mixed, with Hungary's János Kádár expressing support, while Soviet leader Leonid Brezhnev and others grew concerned about Dubček's reforms, which they feared might weaken the Eastern Bloc's position during the Cold War.[31][32] On 3 August, representatives from the Soviet Union, East Germany, Poland, Hungary, Bulgaria, and Czechoslovakia met in Bratislava and signed the Bratislava Declaration, which declaration affirmed unshakable fidelity to Marxism-Leninism and proletarian internationalism and declared an implacable struggle against "bourgeois" ideology and all "anti-socialist" forces.[33]

On the night of 20–21 August 1968, Eastern Bloc armies from four Warsaw Pact countries – the Soviet Union, Bulgaria, Poland and Hungary – invaded Czechoslovakia.[34][35] The invasion comported with the Brezhnev Doctrine, a policy of compelling Eastern Bloc states to subordinate national interests to those of the Bloc as a whole and the exercise of a Soviet right to intervene if an Eastern Bloc country appeared to shift towards capitalism.[36][37] The invasion was followed by a wave of emigration, including an estimated 70,000 Czechs initially fleeing, with the total eventually reaching 300,000.[38] In April 1969, Dubček was replaced as first secretary by Gustáv Husák, and a period of "normalization" began.[39] Husák reversed Dubček's reforms, purged the party of liberal members, dismissed opponents from public office, reinstated the power of the police authorities, sought to re-centralize the economy and re-instated the disallowance of political commentary in mainstream media and by persons not considered to have "full political trust".[40][41] The international image of the Soviet Union suffered considerably, especially among Western student movements inspired by the "New Left" and non-Aligned Movement states. Mao Zedong's People's Republic of China, for example, condemned both the Soviets and the Americans as imperialists.

Soviet "military advisors" played an important role in at least four wars:

• The Angolan Civil War (1975–92), where the USSR supported the left-wing MPLA;
• The Mozambican Civil War (1977–92), where Moscow also sided with Socialist government;
• The Ogaden War between Ethiopia and Somalia (1977–78).
• War of Attrition between Arab countries and Israel.
• Vietnam War between North Vietnam, and South Vietnam and USA.
• Congo Crisis, where USSR backed Republic of the Congo against Katanga Province.
• Operation Trikora : The Indonesian operation to seize Netherlands New Guinea was backed by Soviet troops manning submarines.

Soviet infantry at the time of deployment

During a 1978 coup d' état in Afghanistan, where the communist party took power, it started a series of radical modernization reforms throughout the country that were forced and deeply unpopular, particularly among the more traditional rural population and the established traditional power structures.[42] The regime's nature[43] of vigorously suppressing opposition, including executing thousands of political prisoners, led to the rise of anti-government armed groups, and by April 1979 large parts of the country were in open rebellion.[44] The ruling party itself experienced deep rivalries, and in September 1979 the President, Nur Mohammad Taraki, was murdered under orders of the second-in-command, Hafizullah Amin, which soured relations with the Soviet Union. Eventually the Soviet government, under leader Leonid Brezhnev, decided to deploy the 40th Army on 24 December 1979.[45] Arriving in the capital of Kabul, they staged a coup,[46] killing president Amin and installing Soviet loyalist Babrak Karmal from a rival faction.[47] The deployment had been variously called an "invasion" (by Western media and the rebels) or a legitimate supporting intervention (by the Soviet Union and the Afghan government)[48][49] on the basis of the Brezhnev Doctrine.

In January 1980, foreign ministers from 34 nations of the Islamic Conference adopted a resolution demanding "the immediate, urgent and unconditional withdrawal of Soviet troops" from Afghanistan.[50] The UN General Assembly passed a resolution protesting the Soviet intervention by a vote of 104 (for) to 18 (against), with 18 abstentions and 12 members of the 152-nation Assembly absent or not participating in the vote;[51][52] only Soviet allies Angola, East Germany and Vietnam, along with India, supported the intervention.[53] Afghan insurgents began to receive massive amounts of aid and military training in neighboring Pakistan and China,[54] paid for primarily by the United States and Arab monarchies in the Persian Gulf.[55][56][57][58][59][60][61][62]As documented by the National Security Archive, "the Central Intelligence Agency (CIA) played a significant role in asserting U.S. influence in Afghanistan by funding military operations designed to frustrate the Soviet invasion of that country. CIA covert action worked through Pakistani intelligence services to reach Afghan rebel groups."[63] Soviet troops occupied the cities and main arteries of communication, while the mujahideen waged guerrilla war in small groups operating in the almost 80 percent of the country that was outside government and Soviet control, almost exclusively being the rural countryside.[64] The Soviets used their air power to deal harshly with both rebels and civilians, levelling villages to deny safe haven to the mujahideen, destroying vital irrigation ditches, and laying millions of land mines.[65][66][67][68]

The international community imposed numerous sanctions and embargoes against the Soviet Union, and the U.S. led a boycott of the 1980 Summer Olympics held in Moscow. The boycott and sanctions exacerbated Cold War tensions and enraged the Soviet government, which later led a revenge boycott of the 1984 Summer Olympics held in Los Angeles.[69] The Soviets initially planned to secure towns and roads, stabilize the government under new leader Karmal, and withdraw within six months or a year. But they were met with fierce resistance from the guerillas,[70] and were stuck in a bloody war that lasted nine years.[71] By the mid-1980s, the Soviet contingent was increased to 108,800 and fighting increased, but the military and diplomatic cost of the war to the USSR was high.[72] By mid-1987 the Soviet Union, now under reformist leader Mikhail Gorbachev, announced it would start withdrawing its forces after meetings with the Afghan government.[73][74] The final troop withdrawal started on 15 May 1988, and ended on 15 February 1989, leaving government forces alone in the battle against the insurgents, which continued until 1992 when the former Soviet-backed government collapsed. Due to its length, it has sometimes been referred to as the "Soviet Union's Vietnam War" or the "Bear Trap" by the Western media.[75][76][77] The Soviets' failure in the war[78] is thought to be a contributing factor to the fall of the Soviet Union.[79]

As many as a 620,000 Soviet troops participated in the nine-year occupation, and 11,897 were killed and 51,367 were wounded.[80] More than 1,000,000 Afghans—mostly civilians—were killed, and at least 4,000,000 were externally displaced by the fighting.