During the Civil War, Confederate soldiers made a biological attack on Union soldiers by dumping animal carcasses into the wells (dshs.state.tx.us). As history progressed, the weapons were no longer human or animal carcasses, but instead moved into deadly microscopic specimens. World War II experienced many advancements in warfare methods, which included improvements in the bioterrorism methods. A Japanese military unit began testing the lethal effects of diseases, such as anthrax, cholera, and typhoid to be used against the Chinese army. The Cold War caused the United States to seek advancements in biological agents to be used against the USSR, which prompted research into techniques to effectively spread these diseases, such as by using biological bombs, aerosols, and through missile launch. Even in the Twenty-First century, biological terrorism has continued to exist. In 2001, the United States caught a true glimpse into the very real possibility of a biological terrorist attack when anthrax laced letters were sent to high profile politicians and journalists