In April 1945, American and Soviet soldiers met on the Elbe River in Germany, shook hands, swapped cigarettes and posed for photographs. Within three years their governments were planning for war against each other. The Cold War was a rivalry between the United States and the Soviet Union, and the blocs around them, that lasted from the end of the Second World War until 1991. It was called cold because the two superpowers never fought each other directly in a full scale war, though millions died in wars fought around them. It shaped borders, economies, science, art and the daily fears of people on every continent.

Two winners with different wounds

The two countries came out of the war in very different shape. The Soviet Union lost roughly 27 million people in the Second World War, more than any other country, and much of its western territory lay in ruins. The United States lost about 400,000 people, suffered almost no damage at home, produced around half of the world's manufactured goods and alone possessed the atomic bomb. Each side read the postwar world through its own experience.

For Soviet leaders, the lesson was security. Germany had invaded Russia twice in a generation, both times across Poland. Stalin wanted friendly governments on his western border, and by friendly he came to mean governments run by local communist parties loyal to Moscow. For American leaders, the lesson was that appeasing dictators in the 1930s had led to catastrophe, and that a world of closed trading blocs had fed depression and war. They wanted open trade, free elections and international institutions. Each side saw its own aims as defensive and the other's as expansion.

Yalta, Potsdam and Eastern Europe

At the Yalta conference in February 1945, Roosevelt, Churchill and Stalin agreed to divide Germany into occupation zones and promised free elections in liberated Eastern Europe. At Potsdam in July and August 1945, with Truman now president, the disagreements sharpened. Over the next three years, communist parties backed by the Red Army took power across Eastern Europe through rigged elections, pressure on rival parties and, in Czechoslovakia in February 1948, a coup. Western leaders saw broken promises. Soviet leaders replied that Britain and the United States had shaped the governments of Italy, Greece and Japan without asking Moscow.

Reading the other side

Each government produced a famous diagnosis of the other. In February 1946 the American diplomat George Kennan sent the Long Telegram from Moscow. The Long Telegram argued that Soviet hostility came from the regime's own insecurity and ideology rather than from anything the West had done, and that Soviet power would pull back when it met firm resistance. In September 1946 the Soviet ambassador in Washington, Nikolai Novikov, sent home his own report claiming that the United States was bent on world domination, building bases around the globe and preparing for a new war. In March 1946, speaking in Fulton, Missouri, Winston Churchill warned that a barrier had come down across Europe from the Baltic to the Adriatic, cutting off the old capitals of the east. Churchill's image of an iron curtain dividing the continent became the name for the line between the two halves of Europe.

The Truman Doctrine and the Marshall Plan

In March 1947, asking Congress for aid to Greece and Turkey, Truman said the United States should support free peoples resisting armed minorities or outside pressure. The Truman Doctrine committed the United States to helping countries resist communist pressure, and it framed the conflict as a global contest between two ways of life. In June 1947 Secretary of State George Marshall proposed a large recovery program. The Marshall Plan gave Western Europe about 13 billion dollars in aid from 1948 to 1952. It was offered to the Soviet bloc as well, but Moscow refused and pressed Poland and Czechoslovakia to refuse too, seeing the plan as a tool of American economic control. In September 1947 the Soviet official Andrei Zhdanov described a world split into two camps, and Moscow set up the Cominform to coordinate communist parties.

Who started it?

Historians have argued about responsibility for decades. The orthodox view blamed Soviet expansion: Stalin's drive to control Eastern Europe and spread communism forced the West to respond. From the late 1950s, revisionist historians blamed American economic expansion, arguing that Washington's hunger for open markets and its use of the atomic bomb as leverage alarmed a battered Soviet Union. Post-revisionists stressed mutual misperception, in which each side's defensive moves looked like aggression to the other. When Soviet archives partly opened in the 1990s, many scholars, including John Lewis Gaddis, concluded that Stalin's suspicion and ambitions mattered more than revisionists had allowed, while still granting that American choices raised the temperature.

Worked example: Greece, 1947

In early 1947 Britain told Washington it could no longer afford to back the Greek government against communist insurgents in a civil war. Try each view. An orthodox reading sees a Soviet push toward the Mediterranean that had to be stopped. Yet Stalin had largely kept his 1944 bargain with Churchill that Greece belonged to the British sphere, and most outside help for the Greek communists came from Tito's Yugoslavia, not Moscow. A revisionist reading notes that the Greek government was itself harsh and that Washington used a local civil war to launch a global policy. A post-revisionist reading sees both: real fear in Washington, real communist ambitions in the Balkans, and a speech that turned a regional problem into a universal crusade. In narrow terms the aid worked, and the insurgents were defeated by 1949. The broader lesson is how quickly a local conflict could be absorbed into the superpower story, a pattern that would repeat across the world.