Just as the 1960s started, a new American President entered the White House. The Cold War was about to enter its most critical phase, when the world would be pushed to the brink of nuclear war.

John F Kennedy took office in January 1961 bringing with him an uncompromising attitude towards the Soviet Union and international communism.
At the Yalta Conference of 1945, Germany, and its capital Berlin, were both divided into four zones of occupation.
Berlin lay well inside the Soviet zone of occupation and was a source of tension throughout the Cold War. This had first become apparent in 1948 with the crisis over the Berlin Blockade.
On 13 August 1961, the Soviet authorities in East Germany sealed off East Berlin by constructing a huge barbed wire barrier. This was soon replaced by a concrete wall, complete with lookout towers and armed guards who had orders to shoot anyone trying to cross into the Western sector.

Throughout the 1950s thousands of East German citizens had fled through Berlin for the West, leaving behind the harsh political climate and economic misery of life under communism. Many of those who defected were educated or highly skilled workers and the East German authorities could not afford to lose their best and brightest citizens.
During the 1950s travel was relatively easy between the Eastern and Western sectors of Berlin. People living under communism in the Eastern sector could visit the West and see for themselves what capitalism could offer. There was decent housing, shops full of goods to buy and relative freedom: all provided by the Western Allies. Many East Germans voted with their feet and this was an embarrassment for the communist authorities.
Berlin was a Western island in a communist sea – an ideal place for American spies to gather intelligence on the Soviet military.