On 1 May, 1960 the Soviets shot down an American U2 spy plane.
The Americans admitted it was a spy plane when the Russians revealed they had captured the pilot, Gary Powers.
A summit meeting in Paris had been arranged before the plane was shot down. Soviet Leader Nikita Khrushchev and US President Dwight D.Eisenhower were due to discuss Berlin and the arms race.
The Soviet leader demanded Eisenhower apologise. The US President refused and Khrushchev abandoned the summit.
USA and USSR relations deteriorated as a result. Khrushchev looked for alternative solutions to the Berlin issue. At the Vienna Summit in 1961, US President Kennedy refused to remove NATO troops from Berlin. Tensions increased further.
On 13 August 1961, Khrushchev and East German leader, Walter Ulbricht ordered the closure of the border between East and West Berlin.
East German police and soldiers sealed the most common border crossings with barbed wire.
On 17 August 1961, Soviet troops began to replace the wire with a concrete wall that stretched over a hundred miles. It ran not only through the centre of Berlin, but wrapped around West Berlin, cutting it off from East Germany.
The Berlin Wall became heavily fortified with watch-towers, anti-tank devices, ditches, barbed wire, guard dogs, powerful searchlights and minefields to prevent escapes.
Buildings overlooking the Wall were demolished or had their windows bricked up so that people could not jump from them. The only legal way across the border was through heavily-guarded checkpoints.
The East German government now had complete control over their sector of the city and could stop the flow of people to the West.
East Germany was brought under control. A possible war between NATO and the Warsaw Pact, resulting from the build-up of tension over West Berlin, was averted.
This can be seen as a failure for communism. Khrushchev and Ulbright forced East Germans to stay instead of them voluntarily living under communism. It was a great propaganda victory for President Kennedy and the West. Although Soviets referred to the Wall as the
anti-fascist protective barrier, it became known as the
wall of shame throughout the world.
It is estimated that over 260 people died trying to escape. But many thousands found ways to the West. They dug tunnels, used hot air balloons and hid in cars.
Western leaders protested but there was little they could do. The East Germans calculated that the Western powers would not risk a war to stop them putting up the Berlin Wall. In 1963, President Kennedy visited Berlin to reassure Berliners that America would not abandon them.