Florida senior Senator Bill Nelson is demanding immediate answers of the Army regarding the Pentagon’s accidental anthrax shipment.

Sen. Nelson asked for a full explanation of safety measures in a letter he sent Thursday to the Secretary of the Army.

“It is crucial that the Department of Army explain the nature and scope of these biological weapons-related activities and the measures used to keep the public and its personnel safe,” Nelson said. “While the Army says it is confident no one has been harmed, it needs to tell us what is being done immediately to prevent this from happening again.”

Nelson reiterated that the army should be prepared to discuss how samples are being shipped to other labs.

The Pentagon announced that it accidently shipped live anthrax to a U.S. base in South Korea and to several labs in as many as nine states across the country. The anthrax samples were also shipped to commercial labs in Texas, Maryland, Wisconsin, Delaware, New Jersey, Tennessee, New York, California and Virginia.

It's not unusual for the Army to ship inactive anthrax samples. The federal government runs an anthrax-vaccine program. The army maintains samples for testing in the event troops are infected with the pathogen.

In this case, the army said they attempted to deactivate the samples, but for some reason the procedure was unsuccessful

The situation remains under investigation.

Some information from the Associated Press was used in this story.