Due to the rapid advancement of various sciences and mass media, overt assassinations and open terrorist operations have taken on a reprehensible form among governments and people worldwide. Therefore, terrorist groups supported by major powers—specifically Western intelligence agencies, particularly Eastern bloc countries—have turned to silent terrorist actions to avoid arousing public sensitivity. On the other hand, given scientific advancements and research in nanotechnology, terrorist groups have managed to generate widespread fear in society using very small amounts of biological materials and poisons. Furthermore, intelligence agencies seeking to quietly assassinate opposition leaders, particularly popular figures, in a way that makes their deaths appear natural have heavily utilized these tools. Additionally, some countries (via their intelligence services) have used pests and destroyed agricultural products of target nations to exert economic pressure and enforce their demands.