S. Popov: The American concept of biological warfare was more tactical in nature, while the Soviet concept, it had a strategic nature. War between continents, war between systems. And so... and so even if someone died on your own side, was that so important? That was, ultimately, one of the fundamental principles of Marxist... the Marxist-Leninist notion of revolution, right? Even if the revolution resulted in human suffering and in the death of some, still and all, the revolutionary cause was more important, right? So, I think that the concepts were different, and to a significant degree, ideological principles had an impact on what happened.