An explosion occurred in the Paris subway system on September 6. The explosion took place between stations Porte de Vincennes and Nation Station. Urgent measures were taken for the evacuation of passengers.
According to one of the versions, the explosion occurred as a result of mechanical problems in the work of the subway system near Nation Station. Presumably, a transformer caught fire. There was a flare and fireworks of sparks, eyewitnesses say.
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The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969