A broader understanding of biosecurity that is emerging under threat of biological warfare, and the fear that such economically devastating events as the mad cow disease epidemic could recur, either deliberately (as an act of bioterrorism) or by accident due to unrestricted imports, is causing some nations, notably New Zealand, to adopt relatively harsh restrictions against imported organisms. As one objective of asymmetric warfare is to cause attacks to appear initially as accidents, or blame slow responses on apparently incompetent governments, there is some concern that spreading a virulent organism among animals would be an effective way to attack humans, damage economies, and discredit governments who are lax on biosecurity. Technologies for scanning for dangerous organisms at ports and markets are also becoming more reliable and less expensive.