How they knew is not to difficult. They manufactured it in their own laboratories (as some prophecies foretold would happen). They were careless and reckless with doing such, but it served their agenda for making such a weapon of mass destruction. They communist dictator government lies like a dog and even have the gull to blame other countries, such as America, for creating the bio-weapon. We will make it through this time, but the next will be much much much more deadly and they are evil enough to do such in those communistic led countries. When our Lady of Garabandal said, "when things are at their worst and when communism returns" she did not say it would return through conventional weapon's such as guns and bullet's (though that will be the case one day as well). Communism is much much much more ruthless than this. It seeks to kill and destroy by any means. Communism also lies, lies, lies.... so one cannot gauge just how bad it is there either.