The Pentagon has admitted that the U.S. military has accidentally sent live samples of anthrax spores to laboratories in nine states, as well as a U.S. air base in South Korea. Four Defense Department Workers have been placed in post-exposure treatment, in order to protect them from the possible effects of exposure to the noxious bacteria.

Anthrax becomes a deadly illness called inhalation anthrax. Cases such as this occurred in 2001, when live samples of the bioweapon were sent through the U.S. mail to government and media agencies. Five people were killed in the incident, according to Reuters.

The live samples were accidentally sent to laboratories in Maryland, Texas, Wisconsin, Delaware, New Jersey, Tennessee, New York, California and Virginia.

Colonel Steve Warren, the acting Pentagon press secretary, stated that despite the exposure, there is no imminent threat to the public, according to The Guardian.

"No personnel have shown any signs of possible exposure. The sample was destroyed in accordance with appropriate protocols," he said.

"All personnel were provided appropriate medical precautionary measures to include examinations, antibiotics and in some instances, vaccinations. None of the personnel have shown any signs of possible exposure," he added.

Jason McDonald, a Centers for Disease Control and Prevention spokesman stated that a full investigation will be conducted regarding the incident, and that the CDC will be working closely with the Defense Department to determine how the incident happened, according to CNN.

"CDC is working in conjunction with state and federal partners to conduct an investigation with all the labs that received samples from the DOD," he said.

"The ongoing investigation includes determining if the labs also received other live samples, epidemiologic consultation, worker safety review, laboratory analysis and handling of laboratory waste," he said.

Warren, however, has ensured that the DOD has already begun taking steps in order to make sure the threat does not escalate.

"The DOD lab was working as part of a DOD effort to develop a field-based test to identify biological threats in the environment," he said.

"Out of an abundance of caution, DOD has stopped the shipment of this material from its labs pending completion of the investigation," he added.