A research lab run by the U.S. military in Utah that deals with highly-infectious diseases inadvertently sent live Anthrax spores to facilities in nine states as well as one military base in South Korea, Pentagon officials confirmed Wednesday.

As the Washington Post reports:

Despite assurances from the Pentagon, Dr. Richard Besser, the former head of the Anthrax Unit at the Centers for Disease Control, told ABC News that the mistake should not be downplayed, because of the seriousness of a disease that kills more than 80% of humans who are exposed to it. “This is a big deal,” Dr. Besser said. “Not because anyone has gotten sick, but because the potential was there. You’re allowed to ship through commercial means, but when you do the precautions are very different. If one of the packages had burst open in transit, it could have been deadly.”