---
title: "The Cold War from Origins to Détente Explained"
description: "Trace the Cold War from Yalta and the Truman Doctrine through crises and alliance blocs to the 1970s thaw codified by SALT I and the Helsinki Accords for your"
url: "https://modeldiplomat.com/learn/lessons/exam-world-history-the-cold-war-origins-to-detente"
---

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The Cold War: origins to détente

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# The Cold War: origins to détente

Cold War origins through détente: from Yalta and the Truman Doctrine to crises, alliance blocs, and the 1970s thaw codified by SALT I and Helsinki.

## From Grand Alliance to Iron Curtain

The Cold War was the global ideological, geopolitical and military rivalry between the United States and the Soviet Union and their respective blocs, conventionally dated from 1947 to 1991. Its origins lay in the unresolved settlement of the Second World War. At the **Yalta Conference (4-11 February 1945)** Roosevelt, Churchill and Stalin agreed on free elections in liberated Europe under the *Declaration on Liberated Europe*; at **Potsdam (17 July-2 August 1945)** the breakdown over German reparations and Polish borders was already visible. George Kennan's **Long Telegram (22 February 1946)** and his 'X' article *The Sources of Soviet Conduct* (Foreign Affairs, July 1947) supplied the intellectual basis of **containment**. Churchill's **'Iron Curtain' speech at Fulton, Missouri (5 March 1946)** named the dividing line.

## The Doctrines of 1947-1949

The rupture crystallised in 1947. The **Truman Doctrine (12 March 1947)** pledged support to Greece and Turkey against communist pressure, committing the US to assist 'free peoples' resisting subjugation. The **Marshall Plan (European Recovery Program, announced 5 June 1947, enacted April 1948)** channelled roughly $13 billion to Western Europe; the USSR refused participation and barred its satellites. Moscow responded with the **Cominform (September 1947)** and the **Molotov Plan**, later institutionalised as **Comecon (1949)**.

Germany became the first flashpoint. The **Berlin Blockade (24 June 1948-12 May 1949)** prompted the Western **Berlin Airlift**, which flew in some 2.3 million tons of supplies. The crisis hardened the division: the **Federal Republic of Germany** and the **German Democratic Republic** were both founded in 1949. Western security was anchored by the **North Atlantic Treaty (4 April 1949)**, whose **Article 5** enshrined collective defence; the Soviet riposte, the **Warsaw Pact**, followed on **14 May 1955** after West German NATO accession.

## Two Shocks of 1949

Nineteen forty-nine delivered two transformative shocks. In August the USSR tested its first atomic bomb, ending the American nuclear monopoly four years after Hiroshima and Nagasaki. In October **Mao Zedong proclaimed the People's Republic of China**, and the **Sino-Soviet Treaty of Friendship (14 February 1950)** appeared to extend the communist bloc across Asia. Together these events transformed a European confrontation into a global contest, codified in the US planning document **NSC-68 (April 1950)**, which called for a vast rearmament. Within months the **Korean War (25 June 1950-27 July 1953 armistice)** turned the Cold War hot, fixing the pattern of proxy conflict, divided states and limited war under the nuclear shadow that would define the next two decades.

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