The Iron Curtain became impenetrable, for people as well as for information. In western nations, the information deficit was felt to be a potential threat to existence. Western secret services could only estimate the strength and equipment of Soviet armed forces by extrapolating from the information provided by former Nazi intelligence officers. The other option was to analyse the research findings of German engineers and gauge the extent to which the Soviets had taken this knowledge on board. These "findings" were, of course, quite imprecise. To make matters worse, German "specialists" were often full of their own importance and exaggerated their knowledge to escape the war tribunals.