Thomas Veale confirmed that DIA discovered "possible biological toxins" that were "potentially harmful" on Tuesday morning during "routine screening" of its incoming mail.

WSJ: Ricin Charges Are Dropped

"Currently, we have identified no infectious agent common to all of the cases, " the statement said, adding that no evidence exists that the cases were caused by exposure to chemical or biological weapons, SARS or environmental toxins.

CNN: Army hunts cause of pneumonia in troops

The U.S. signed on to two accords banning biological and chemical weapons and, pursuant to those treaties, has eliminated all offensive viruses and toxins and is in the process of destroying its stocks of chemical munitions.

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