Declassified intelligence reports have shed new light on one of history's greatest "what-ifs", the building of the Berlin Wall 40 years ago this weekend.
The CIA, French and German intelligence services all received reports in early August 1961 that Berlin would be divided, casting doubt on claims that the west did not know in advance.
"Records show that on August 6th a high-ranking communist party member told the CIA that the party was 'planning drastic measures' to block off West Berlin the following weekend," wrote a German historian, Mr Klaus Wiegrefe, in Der Spiegel magazine. Another well-placed source told the French secret service in early August: "They want to build a barrier through the middle of Berlin." The documents will be a bitter pill for many Berliners this weekend, who remember how their pleas to the west to intervene went unanswered.
According to documents seen by Der Spiegel, President Kennedy told an adviser after a meeting with Soviet leader Mr Nikita Kruschev in July 1961: "He has to do something to stop the flood of refugees, perhaps build a wall. And we will not be able to prevent that." Since the end of the war, over 2.7 million people had fled from East Germany to Allied Sector in western Berlin, where the price of a suburban train ticket bought freedom.
That ended at 1 a.m. on August 13th, 1961, when 40,000 soldiers took less than five hours to seal 193 streets, 12 train lines and 28 train stations. Would-be refugees who turned up at Friedrichstrasse train station in the early hours of August 13th were sent away.
President Kennedy was informed that the borders had been sealed only 16 hours after it happened. After hearing the news he went sailing. British Prime Minister Macmillan remarked: "Nobody is going to fight over Berlin" and continued his round of golf in Scotland.
Over the next 28 years over 8,000 people tried, but only 5,000 managed to get across the Berlin Wall. Ceremonies are planned around the city this weekend to remember the estimated 240 people who died trying.
