The Cold War: crises and the end, 1957-1991

These notes cover the Cold War from the late 1950s to its end in 1991, within the International History (1945–1991) option of Cambridge International AS & A Level History (9489). They trace the Berlin Crisis of 1958-61, the Cuban Missile Crisis of 1962, the move to detente in the 1970s, the return to confrontation after the Soviet invasion of Afghanistan in 1979, the Reagan arms build-up, Gorbachev's reforms, the revolutions of 1989 and the collapse of the USSR in 1991. A dated timeline, named historical interpretations and three essay plans follow the narrative sections.

The Berlin Crisis, 1958-61

By the late 1950s Berlin remained divided into four occupation sectors inside communist East Germany, and West Berlin was an island of Western prosperity and an open crossing point between the two Germanies. East Germany was losing population steadily through West Berlin: around three million people crossed to the West between 1949 and 1961, many of them young and skilled, damaging the East German economy. Khrushchev also resented Western troops remaining deep inside what he regarded as the Soviet sphere.

On 27 November 1958 Khrushchev issued the Berlin Ultimatum, demanding that the Western powers withdraw from West Berlin within six months and that it become a demilitarised "free city," or the USSR would hand control of access routes to East Germany. The West refused to be moved. A Geneva conference in 1959 reached no settlement, and at Camp David in September 1959 Eisenhower and Khrushchev agreed to keep talking, producing a brief thaw. This collapsed when a US U-2 spy plane was shot down over Soviet territory on 1 May 1960, and Khrushchev used the incident to wreck the Paris summit that month.

Khrushchev renewed pressure at the Vienna summit of June 1961, judging the new US president, John F. Kennedy, weakened by the failed Bay of Pigs invasion of Cuba some six weeks earlier. Refugee numbers surged again in 1961, reaching over a thousand people a day by summer. On the night of 12-13 August 1961 East German forces sealed the border with barbed wire, rapidly replaced by a concrete wall with watchtowers, encircling West Berlin. In October 1961 a dispute over an American diplomat's right to cross into East Berlin brought Soviet and American tanks face to face at Checkpoint Charlie for sixteen hours before both sides withdrew.

Key idea to learn: the Berlin Wall did not cause the Cold War crisis over Berlin; it ended it. By stopping the refugee flow it removed Khrushchev's main grievance, and neither side went to war over it. It became instead the most visible symbol of a divided Europe for the next twenty-eight years, referred to by Kennedy in his June 1963 "Ich bin ein Berliner" speech as proof of the failure, not the success, of the communist system.

The Cuban Missile Crisis, 1962

Causes

Fidel Castro's revolutionary government, in power in Cuba since January 1959, moved towards the Soviet Union after the United States imposed a trade embargo and after the CIA-backed Bay of Pigs invasion of April 1961 failed to overthrow him. Khrushchev had three motives for placing nuclear missiles on Cuba in 1962: to correct the wide gap in long-range missiles, in which the United States held a clear lead; to defend Cuba against a feared second US invasion; and to gain leverage over the question of West Berlin and of American Jupiter missiles already stationed in Turkey and Italy, within easy reach of Soviet territory.

The thirteen days

A U-2 flight on 14 October 1962 photographed missile sites under construction, and the pictures reached Kennedy on 16 October. His advisory group, ExComm, debated an air strike, a full invasion and a naval blockade before Kennedy chose a "quarantine," announced to the public on 22 October 1962. Soviet ships bound for Cuba turned back on 24 October rather than force a confrontation. Work on the sites continued, and on 27 October an American U-2 was shot down over Cuba, killing its pilot, Major Rudolf Anderson.

Khrushchev sent two letters. The first, on 26 October, offered to remove the missiles for a US pledge not to invade Cuba. The second, on 27 October, was tougher, adding a demand that the US remove its Jupiter missiles from Turkey. Robert Kennedy, the president's brother, met the Soviet ambassador Anatoly Dobrynin, and the administration publicly accepted the first letter's terms while ignoring the second; privately, Robert Kennedy promised the already-obsolete Turkish missiles would be withdrawn quietly within months. On 28 October Khrushchev announced the missiles would be dismantled.

Worked example — building an answer on causation: a question might ask "How far was the Cuban Missile Crisis caused by Khrushchev's miscalculation?" Step 1: identify Khrushchev's calculation (secrecy would let the missiles become operational before discovery). Step 2: show where it failed (US surveillance detected the sites before completion, and Kennedy chose confrontation). Step 3: weigh this against structural causes independent of any one leader (the missile gap, the Bay of Pigs failure, Cuba's search for a protector). Step 4: reach a supported judgement — for example, that the immediate trigger was Khrushchev's poorly concealed gamble, but the underlying cause was the wider context that made such a gamble attractive to him.

Resolution and consequences

The Soviet Union removed its missiles and, by December 1962, its IL-28 bombers from Cuba, while the United States confirmed it would not invade the island and secretly withdrew the Jupiter missiles from Turkey by April 1963. Both superpowers drew back from a crisis that brought them closer to nuclear war than at any other point in the Cold War. A direct teletype link between Washington and Moscow, the "hotline," was agreed in June 1963, and on 5 August 1963 the two powers and Britain signed the Partial Test Ban Treaty, banning nuclear tests in the atmosphere, space and underwater. Khrushchev's authority was weakened by what many Soviet leaders saw as a humiliating retreat, contributing to his removal from power in October 1964.

The shift to detente

By the late 1960s both superpowers had reasons to seek stability. Nuclear parity had been reached, so any war threatened mutually assured destruction, and the cost of the arms race strained both economies, the Soviet one especially. The Sino-Soviet split gave Moscow an incentive to reduce tension with the West. The United States, absorbed in the Vietnam War, wanted Soviet cooperation in ending it, while West Germany's chancellor Willy Brandt pursued Ostpolitik from 1969, engaging East Germany, Poland and the USSR.

At the Moscow summit of May 1972 Nixon and Brezhnev signed the SALT I agreements: the Anti-Ballistic Missile (ABM) Treaty, limiting each side to a small number of missile-defence sites, and an Interim Agreement freezing numbers of intercontinental and submarine-launched missile launchers for five years. In August 1975 thirty-five states, including the US, Canada, the USSR and nearly all of Europe, signed the Helsinki Final Act, with three "baskets": recognition of existing European borders, economic cooperation, and human rights and free movement. The USSR valued the border guarantees; the human rights basket, treated as a formality by Moscow, was later used by dissidents across Eastern Europe to hold their governments to account.

Key idea to learn: detente meant a relaxation of tension and an increase in cooperation between the superpowers, not the end of rivalry or of competition in the developing world.

Detente had clear limits. Both powers continued backing opposing sides in regional conflicts, including the Angolan civil war from 1975 and the Ogaden war in the Horn of Africa in 1977-78, both involving Cuban troops and Soviet advisers. The Jackson-Vanik Amendment of 1974 linked US trade concessions to Jewish emigration from the USSR, angering Moscow, and SALT II, signed in 1979, was never ratified by the Senate. Detente was effectively ended by the Soviet invasion of Afghanistan at the close of 1979.

The Soviet invasion of Afghanistan and the return to confrontation

A communist party, the PDPA, seized power in Afghanistan in the Saur Revolution of April 1978 and pushed through reforms that provoked a widespread rural and Islamist rebellion. Power struggles within the party culminated in September 1979 when Hafizullah Amin ousted the previous leader, Nur Muhammad Taraki, and had him killed the following month. Fearing Amin could not hold the country, and that Afghanistan might fall to Islamist forces close to revolutionary Iran, Soviet troops entered Afghanistan between 24 and 27 December 1979, killed Amin and installed Babrak Karmal.

The invasion ended detente. President Carter announced the Carter Doctrine in January 1980, pledging US force to defend its interests in the Gulf, withdrew SALT II from Senate consideration, imposed a grain embargo, and led a boycott by around sixty-five nations of the 1980 Moscow Olympics. Through Pakistan's intelligence service the CIA armed the Afghan mujahideen under Operation Cyclone, turning Afghanistan into a costly proxy war often compared to the American experience in Vietnam.

Reagan's policies and the arms race

Ronald Reagan, elected US president in 1980, abandoned detente's language for open confrontation, describing the Soviet Union as an "evil empire" in March 1983. His administration greatly increased defence spending and, following NATO's 1979 "dual-track" decision, deployed Pershing II and cruise missiles to Western Europe from late 1983 against Soviet SS-20 missiles, provoking mass protests but going ahead. Tension peaked in 1983: Korean Air Lines Flight 007 was shot down after straying into Soviet airspace in September, killing 269 people, and the NATO exercise Able Archer in November was briefly, mistakenly read by Soviet intelligence as cover for a real first strike.

On 23 March 1983 Reagan announced the Strategic Defense Initiative (SDI), a proposed space-based system to shoot down incoming missiles. Whether it could ever have worked is disputed, but its likely effect was to threaten the strategic balance and force the USSR to consider matching a project its strained economy could not afford. Historians dispute how far this pressure was decisive rather than symbolic, a debate developed further in the interpretations section below. Behind the confrontation the Soviet leadership was ageing: Brezhnev died in 1982, Andropov in 1984, Chernenko in 1985, leaving the Politburo to choose a younger figure, Mikhail Gorbachev, in March 1985.

Gorbachev's reforms and their effect on Eastern Europe

Gorbachev inherited a stagnant economy, a costly war in Afghanistan, and a leadership out of touch with a society whose problems could no longer be hidden. From 1986 he promoted two connected policies. Glasnost ("openness") relaxed censorship and allowed public criticism, a shift tested dramatically when the Chernobyl nuclear disaster of April 1986 exposed the state's instinct to conceal bad news as radiation spread across Europe. Perestroika ("restructuring") introduced limited market mechanisms and independence for state enterprises, but disrupted the planned economy faster than it built a replacement, and shortages worsened during the later 1980s.

Key idea to learn — define both terms precisely: glasnost was a policy of greater political openness and freedom of expression; perestroika was a policy of economic and administrative restructuring intended to make socialism more efficient, not to replace it with capitalism. Each exposed the weaknesses of the other, since open criticism made the failures of restructuring impossible to hide.

In foreign policy Gorbachev pursued "new thinking," seeking to cut the costs of the arms race. He met Reagan at Geneva in 1985, at Reykjavik in October 1986, where the two nearly agreed to eliminate all nuclear weapons before talks broke down over SDI, and at Washington in December 1987, signing the Intermediate-Range Nuclear Forces (INF) Treaty, the first agreement to eliminate a whole class of nuclear weapons. Soviet troops withdrew from Afghanistan, completing the process in February 1989. Historians such as Archie Brown see this shift in thinking as evidence of Gorbachev's own ideological conviction, discussed further below, rather than simply a response to Western pressure.

Gorbachev also abandoned the Brezhnev Doctrine, under which Moscow had reserved the right to intervene militarily to preserve communist rule in Eastern Europe, as in Hungary in 1956 and Czechoslovakia in 1968. His refusal to prop up unpopular regimes by force, sometimes called the "Sinatra Doctrine," removed the ultimate guarantee that had kept communist governments in power and opened the way to the events of 1989.

The revolutions of 1989 and the fall of the Berlin Wall

Change came first in Poland, where the independent trade union Solidarity, banned since 1981, was legalised again in early 1989. Round-table talks ran from February to April 1989, and partially free elections on 4 June 1989 produced a Solidarity landslide; by September a Solidarity-led government under Tadeusz Mazowiecki took office, the first non-communist government in the Soviet bloc since the 1940s. In Hungary reformist communists dismantled the barbed-wire border with Austria in May 1989, and on 19 August 1989 a "Pan-European Picnic" let hundreds of East Germans cross into the West through the gap, an early sign the Iron Curtain was breaking down.

East Germany faced a mounting exodus through Hungary and Czechoslovakia in autumn 1989, alongside weekly "Monday demonstrations" in Leipzig. Leader Erich Honecker resigned on 18 October 1989. On 9 November 1989 spokesman Günter Schabowski mistakenly announced that new travel rules would take effect immediately; crowds gathered at the checkpoints that night, and overwhelmed border guards opened the crossings. The Berlin Wall was breached within hours, and Berliners tore down sections of it in the days that followed.

Key idea to learn: almost all the 1989 revolutions were peaceful and were driven by internal opposition movements and mass demonstrations, not by outside force; Gorbachev's central contribution was refusing to send in Soviet tanks, not instigating the changes himself.

Czechoslovakia's Communist government fell within weeks in the largely peaceful "Velvet Revolution" of November-December 1989, and the playwright Vaclav Havel became president by year's end. Bulgaria's leader Todor Zhivkov was removed by his own party on 10 November 1989. Only in Romania did change turn violent: the dictator Nicolae Ceausescu was overthrown and, with his wife, executed after a short trial on 25 December 1989. By the close of 1989 communist rule had ended across Eastern Europe.

The collapse of the Soviet Union, 1991

Nationalist movements grew rapidly inside the Soviet Union once Gorbachev's reforms had loosened political control, especially in the Baltic republics, where Lithuania declared independence in March 1990. Economic conditions worsened, and Gorbachev's authority was squeezed between reformers led by Boris Yeltsin, elected president of the Russian republic in June 1991, and hardliners who blamed him for losing Eastern Europe.

Hardliners calling themselves the State Committee on the State of Emergency attempted a coup on 19 August 1991 while Gorbachev was on holiday in Crimea, placing him under house arrest. Yeltsin rallied resistance from the Russian parliament building, and popular defiance, the coup leaders' hesitation and the army's reluctance to fire on civilians caused it to collapse by 21 August. The coup fatally weakened both Gorbachev and the Communist Party, soon suspended, while Yeltsin emerged as the dominant figure.

Republic after republic then declared independence. On 8 December 1991 the leaders of Russia, Ukraine and Belarus signed the Belavezha Accords, declaring the Soviet Union ceased to exist and forming a Commonwealth of Independent States; most other republics joined at Alma-Ata on 21 December 1991. Gorbachev, president of a state no republic wished to remain part of, resigned on 25 December 1991, and the Soviet Union was formally dissolved the next day.

Timeline

Date	Event
27 November 1958	Khrushchev's Berlin Ultimatum
September 1959	Camp David meeting, Eisenhower and Khrushchev
1 May 1960	U-2 spy plane shot down over the USSR; Paris summit collapses
April 1961	Bay of Pigs invasion of Cuba fails
June 1961	Vienna summit, Kennedy and Khrushchev
12-13 August 1961	Construction of the Berlin Wall begins
16-28 October 1962	Cuban Missile Crisis
June 1963	Moscow-Washington hotline agreement signed
5 August 1963	Partial Test Ban Treaty signed
1969 onward	Willy Brandt's Ostpolitik
May 1972	SALT I and ABM Treaty signed, Moscow
August 1975	Helsinki Final Act signed
1975-78	Proxy conflicts in Angola and the Horn of Africa
24-27 December 1979	Soviet invasion of Afghanistan
January 1980	Carter Doctrine announced
1980	US-led boycott of the Moscow Olympics
November 1980	Ronald Reagan elected US president
March 1983	Reagan's "evil empire" speech; SDI announced
September 1983	Korean Air Lines Flight 007 shot down
November 1983	Able Archer 83 exercise and Soviet war scare
March 1985	Gorbachev becomes General Secretary
April 1986	Chernobyl nuclear disaster
October 1986	Reykjavik summit
December 1987	INF Treaty signed, Washington
February 1989	Soviet troops complete withdrawal from Afghanistan
June 1989	Solidarity wins Polish elections
9 November 1989	Fall of the Berlin Wall
25 December 1989	Ceausescu executed in Romania
March 1990	Lithuania declares independence
19-21 August 1991	Attempted coup against Gorbachev
8 December 1991	Belavezha Accords dissolve the USSR
25-26 December 1991	Gorbachev resigns; Soviet Union formally ends

Historical interpretations: why did the Cold War end?

Historians disagree sharply about which factor mattered most, and examiners expect named interpretations rather than unattributed opinion.

One school, associated with writers sympathetic to Reagan's record and reflected in parts of John Lewis Gaddis's later work, argues that sustained Western pressure, above all the arms build-up and SDI, pushed a Soviet economy that could not keep pace into crisis, leaving Gorbachev little choice but to seek accommodation. This "peace through strength" view credits Reagan's confrontation, continued into the mid-1980s, as decisive.

A second interpretation puts Gorbachev's own choices at the centre. Historian Archie Brown argues the end of the Cold War depended on Gorbachev's personal ideological conversion to "new thinking" and his voluntary abandonment of the Brezhnev Doctrine; a different Soviet leader committed to the old orthodoxy could have continued the confrontation regardless of Reagan's policies.

A third interpretation, associated with Raymond Garthoff, stresses mutual learning: both sides gradually revised assumptions about the other's intentions during the 1980s, and Garthoff is critical of claims that confrontation alone explains the outcome, pointing instead to how Reagan himself moved towards cooperation after 1984. Historian Beth Fischer develops this "Reagan reversal" thesis directly, arguing that the Able Archer war scare of November 1983 alarmed Reagan personally and pushed him, before Gorbachev took office, towards the conciliatory approach that made the later summits possible.

A fourth, structural interpretation looks past individual leaders to the Soviet system's own weaknesses: decades of low productivity, technological backwardness and an over-extended military made crisis likely regardless of Western policy, so Gorbachev's reforms are best understood as a response to decline already under way rather than its cause.

Key idea to learn: when answering "why did the Cold War end" questions, weigh Western pressure, Gorbachev's agency and Soviet internal weakness against each other, and attribute each interpretation to a named historian or school rather than presenting it as settled fact.

Essay planning guidance

Question 1: "Khrushchev's own miscalculations were the main cause of the Cuban Missile Crisis of October 1962." How far do you agree?

Plan: Introduction — define the question's focus and state a clear line of argument. Paragraph 1 — Khrushchev's own motives: correcting the missile gap, defending Cuba, and the secretive method chosen, which invited discovery. Paragraph 2 — the American contribution: the Bay of Pigs, the embargo, and the Jupiter missiles in Turkey that gave Khrushchev his justification. Paragraph 3 — Cuban agency: Castro's own wish for Soviet protection. Conclusion — weigh the three factors and reach a supported judgement, avoiding a simple "50/50" answer.

Question 2: "Detente collapsed mainly because of the Soviet invasion of Afghanistan in December 1979." How far do you agree?

Plan: Introduction — state that Afghanistan was the immediate trigger, but test it against strains already visible before 1979. Paragraph 1 — the case for Afghanistan: the Carter Doctrine, grain embargo, Olympic boycott and shelving of SALT II all followed directly from the invasion. Paragraph 2 — prior strains: the Jackson-Vanik Amendment, proxy conflicts in Angola and the Horn of Africa from the mid-1970s, and rising US criticism of detente as one-sided. Paragraph 3 — the structural point that detente was always limited, since neither side abandoned competition outside Europe even at its height. Conclusion — judge whether Afghanistan was the decisive final blow or the true single cause.

Question 3: To what extent was Gorbachev personally responsible for the ending of the Cold War by 1991?

Plan: Introduction — set up a debate between Gorbachev's agency and wider forces, referencing named historians. Paragraph 1 — Gorbachev's direct contribution: glasnost, perestroika, new thinking, the INF Treaty, withdrawal from Afghanistan and abandonment of the Brezhnev Doctrine, drawing on Archie Brown. Paragraph 2 — the counter-argument from Western pressure, drawing on the "peace through strength" view, that SDI and the arms build-up left Gorbachev little choice. Paragraph 3 — the structural counter-argument that stagnation made reform or collapse likely under any leader. Conclusion — judge whether Gorbachev's decisions caused the Cold War's end or were the mechanism through which deeper pressures were finally expressed.

Key terms

Term	Definition
Detente	A relaxation of tension and increase in cooperation between the superpowers, without ending underlying rivalry.
Containment	The US strategy of preventing the spread of communism beyond its existing borders.
Brezhnev Doctrine	The Soviet policy that Moscow could intervene militarily to preserve communist rule in any Warsaw Pact state.
"Sinatra Doctrine"	An informal name for Gorbachev's abandonment of the Brezhnev Doctrine, letting Eastern European states choose their own path.
Glasnost	Gorbachev's policy of political openness and freedom of expression, from 1986.
Perestroika	Gorbachev's policy of economic and administrative restructuring, from 1986.
Mutually assured destruction (MAD)	The condition where both superpowers could destroy each other even after absorbing a first strike, deterring either from attacking.
SALT	Strategic Arms Limitation Talks, producing SALT I (1972) and SALT II (1979, unratified), limiting strategic weapon numbers.
ABM Treaty	The 1972 treaty limiting each superpower to a small number of anti-ballistic missile sites.
Hotline	The direct Washington-Moscow link agreed in 1963 to allow rapid contact between leaders in a crisis.
Quarantine	The term used for the Kennedy administration's naval blockade of Cuba in October 1962, chosen because a blockade was technically an act of war.
Proxy war	A conflict in which rival powers support opposing local sides rather than fighting each other directly.
Satellite state	A nominally independent state politically and economically controlled by a more powerful neighbour, as Eastern European states were controlled by the USSR.
Iron Curtain	The political and military boundary dividing communist Eastern Europe from the capitalist West.
Mujahideen	Afghan guerrilla fighters who resisted the Soviet occupation from 1979 to 1989.
Ostpolitik	Willy Brandt's policy from 1969 of improving relations with East Germany and the Soviet bloc.
Helsinki Final Act	The 1975 agreement among thirty-five states covering European borders, economic cooperation and human rights.
SDI (Strategic Defense Initiative)	Reagan's 1983 proposal for a space-based system to intercept incoming missiles, nicknamed "Star Wars."
INF Treaty	The 1987 treaty eliminating an entire class of intermediate-range nuclear missiles.
Commonwealth of Independent States (CIS)	The loose association formed by most former Soviet republics after the USSR's dissolution in December 1991.

Quick check

Items 1-7 are short recall prompts for self-testing revision; the bracketed figures are a rough self-check guide, not the mark scheme used in the 9489 papers, which assess extended "how far/to what extent" essays against level descriptors rather than short-answer points. Items 8-12 mirror that essay-style format and are the better guide to actual exam demand.

1. Define "detente." [2]
2. State two consequences of the Cuban Missile Crisis. [2]
3. Describe the events that led to the building of the Berlin Wall in August 1961. [4]
4. Describe the "thirteen days" of the Cuban Missile Crisis, from discovery to resolution. [6]
5. Explain why the Soviet Union invaded Afghanistan in December 1979. [6]
6. Explain why the Helsinki Final Act of 1975 is considered a high point of detente. [6]
7. Explain how Gorbachev's policies of glasnost and perestroika were connected to each other. [6]
8. "The revolutions of 1989 in Eastern Europe succeeded mainly because Gorbachev chose not to intervene." How far do you agree? [10]
9. To what extent was the Cuban Missile Crisis the most dangerous moment of the Cold War? [10]
10. Assess the view that the Soviet Union's economic weakness, rather than Western pressure, was the main reason the Cold War ended. [10]
11. "Detente was a failure." How far do you agree with this judgement on the 1970s? [10]
12. To what extent was Gorbachev personally responsible for the collapse of the Soviet Union in 1991? [10]

1. A relaxation of tension and increase in cooperation between the superpowers, especially through arms control and diplomacy, without either side abandoning underlying rivalry.

2. Any two of: the Washington-Moscow hotline (1963); the Partial Test Ban Treaty (1963); the weakening of Khrushchev's authority, contributing to his removal in 1964; momentum towards later arms control; Cuban resentment at being used as a bargaining chip.

3. East Germany lost around three million people, many skilled, through the open crossing to West Berlin between 1949 and 1961. The 1958 ultimatum failed to remove Western forces, and tension rose again after Vienna in June 1961, when Khrushchev judged Kennedy weak after the Bay of Pigs. As refugees surged past a thousand a day in summer 1961, East German forces sealed the border on 12-13 August 1961 with barbed wire, quickly replaced by a concrete wall.

4. A U-2 flight on 14 October 1962 photographed missile sites; Kennedy learned on 16 October and convened ExComm. On 22 October he announced a naval "quarantine." Soviet ships turned back on 24 October, but site work continued and a US U-2 was shot down on 27 October. Khrushchev's letters of 26 and 27 October offered removal, the second adding a demand over Turkish missiles; the crisis ended on 28 October with removal of the Cuban missiles for a US non-invasion pledge and a secret withdrawal of the Jupiter missiles from Turkey.

5. The Soviet leadership feared the communist government installed after the 1978 Saur Revolution, especially under Amin after September 1979, could not survive the Islamist-led rebellion, and worried Afghanistan might fall under the influence of revolutionary Iran. The invasion of 24-27 December 1979 removed Amin, installed Babrak Karmal, and reflected the Brezhnev Doctrine's assumption that Moscow could act to preserve a friendly government near its borders.

6. It brought together thirty-five states, including the USSR, the US and nearly all of Europe, combining recognition of existing European borders, valued by Moscow, with commitments on economic cooperation and, in its third "basket," human rights and free movement. Its human rights provisions, though treated lightly by Moscow at the time, later gave dissident and reform movements across Eastern Europe a recognised standard to appeal to.

7. Glasnost opened up debate and criticism, exposing the failures perestroika's restructuring was creating or failing to fix, most dramatically after Chernobyl in April 1986. Perestroika needed public support and honest information to work, which only glasnost could supply. In practice glasnost exposed perestroika's poor performance faster than perestroika could deliver real improvement, so each policy destabilised the other as much as it reinforced it.

8. Agree that Gorbachev's refusal to use force, replacing the Brezhnev Doctrine, was essential, since earlier uprisings in Hungary (1956) and Czechoslovakia (1968) had been crushed by Soviet tanks. But also credit the strength of opposition movements such as Solidarity, mass demonstrations in East Germany and Czechoslovakia, and specific failures such as Schabowski's mistaken announcement on 9 November 1989. Gorbachev's restraint was a necessary condition for peaceful success, but domestic opposition actually brought the regimes down. Note too the peaceful, negotiated model set by Poland's Round Table talks in early 1989 and its replication in Czechoslovakia's Velvet Revolution, showing how opposition strategy, not just Soviet restraint, shaped the outcome.

9. The Cuban Missile Crisis was uniquely dangerous: direct superpower confrontation over nuclear weapons at close range, the US moving to DEFCON 2, and moments, such as the U-2 shot down on 27 October 1962, that could have triggered war by accident. Weigh this against other dangerous moments, such as Able Archer in November 1983, when Soviet intelligence briefly feared a real Western first strike, before concluding which carried the greater risk. Contrast this with the Berlin Wall crisis of 1961, tense but without a comparable nuclear alert, to sharpen the judgement a "most dangerous moment" question requires.

10. Weigh Soviet structural weaknesses — low productivity, technological lag, the cost of the military and satellite empire — against Western pressure such as the arms build-up and SDI, and against Gorbachev's own reforming choices. Reference named interpretations, for example "peace through strength" against the agency-centred view associated with Archie Brown, before reaching a supported judgement on which factor weighed most heavily. Note the alternative stressed by Garthoff and Fischer, who argue Reagan's own shift towards cooperation after 1984 mattered as much as Soviet structural decline in ending the confrontation.

11. Weigh achievements — SALT I, the ABM Treaty, the Helsinki Final Act — against limits: continued proxy conflicts in Angola and the Horn of Africa, the unratified SALT II, and detente's collapse after Afghanistan in 1979. Conclude with a supported judgement on whether detente is better described as a genuine, if limited, success or a failure once its collapse is taken into account. Also weigh how the Jackson-Vanik Amendment damaged trust from 1974 and how proxy competition continued even at detente's height, evidence for the "failure" side of the judgement.

12. Credit Gorbachev's reforms, especially glasnost's loosening of control, which allowed nationalist movements to grow, and perestroika's failure to fix the economy, fuelling the discontent behind the August 1991 coup. Weigh this against long-term Soviet stagnation predating Gorbachev, and Yeltsin's decisive role in defeating the coup and negotiating the Belavezha Accords that dissolved the Union, before reaching a balanced judgement on Gorbachev's degree of personal responsibility. Also weigh the specific trigger of the failed August 1991 coup, which accelerated republics' declarations of independence within weeks, against Gorbachev's longer-term loosening of central control since 1985.