What did all this remind me of? The fall of the Berlin Wall, of course. When on November 9, 1989, the East German government spokesman Günter Schabowski unexpectedly announced on live television that people would be allowed to travel to the West, he was bombarded with questions. Asked when the new policy would come into effect, he rustled his papers, evidently uncertain, and answered: "As far as I know . . . immediately, without delay." I was standing a few yards away from Schabowski and asked my question: "Mr Schabowski, what will happen to the Berlin Wall now?" Nobody had mentioned the Wall up to that point, and Schabowski may have realised at this point that he had gone beyond his brief. He had no answer, because once the Wall was open, there was no rational justification for dividing the city, the country, or indeed Europe. Schabowski began by bringing his torment to an end: "This is the last question, ja!" To give himself time to think, he repeated my question, stuttered and sweated. "The question of travel, er, the permeability of the Wall from our side, does not answer the question of the meaning of this, as I would put it, fortified state border of the GDR." He went on for another paragraph about arms control, before bringing the press conference to a close. 

By this time it was obvious that, if Schabowski's announcement was correct, then the Wall had suddenly lost its raison d'être. Word spread like wildfire among East Berliners, who began to arrive at the checkpoints and demanding to be let through. The border guards had no orders and eventually they let the crowds through — without visas or passports, as had been envisaged by the Politburo. The game was up and within days the demolition of the Wall had begun. Some 20 years later, Schabowski admitted that his role had been "involuntary" and that as a committed Communist he had been trying to save the East German regime, not bring it to an end.

The gaffe that prematurely opened the Berlin Wall was of course welcomed across the world. John Kerry's blunder has not had a comparable impact, but it has still changed the course of history. At the time of writing, the Secretary of State has yet to admit any responsibility for the reversal of US policy. He is famously a big man, but not, apparently, big enough to shoulder the blame. Instead, he is now engaged in a protracted negotiation with his rather brighter Russian counterpart, Sergei Lavrov, which may give the Assad regime the breathing space it requires to win the civil war. And all because one man couldn't keep his mouth shut. As Tennyson put it, someone had blundered.  And that someone is John Kerry.