North Korea filed an official letter to the UN in early June claiming that the U.S. is preparing to launch germ warfare against it, a UN document shows.

The claim stems from the discovery that live anthrax samples may have been shipped to the Osan Air Base in South Korea from the U.S., a discovery North Korea claims shows that the U.S. is preparing for germ warfare against the DPRK.

“The world should brand the scheme of the U.S., which rules out even the preparations for a germ warfare which is strictly banned internationally, as the gravest challenge to peace