On Monday, US President Donald Trump sent his first National Security Strategy report to lawmakers.
The Trump administration also said in its National Security Strategy document released this week that the rogue regime was developing a missile capable of carrying biological weapons.
The source in South Korea said Pyongyang is conducting heat and pressure resistance tests to see whether anthrax germs can survive at temperatures of 7,000 degrees or higher, the level an ICBM encounters when it re-enters Earth's atmosphere.
North Korea has denied the report from the White House.
The threat of an impending war with North Korea intensified after the country's state television reported last month it launched a new intercontinental ballistic missile, Hwasong 15, which is a nuclear-capable weapon that could reach the entire continental U.S.
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According to the Asahi, Washington had allegedly known that North Korea was culturing anthrax for a while. "And the US itself is an empire of evils full of plots, fabrications, lies and deceptions".
The statement went on to accuse the USA of using "bacteriological" weapons during the Korean War.
"To send North Korea a unified message from the global community, that we will not accept you as a nuclear nation", US Secretary of State Rex Tillerson said. A report by Harvard Kennedy School's Belfar Center for Science and International Affairs stated the dictatorship may have "anthrax and smallpox" pathogens that could be turned into weapons.
"It is the U.S. that conducts military aggressions and cruise missile attacks on sovereign states in broad daylight while faking "possession of WMD" and "use of chemical weapons" of those countries", said the statement.
Secretary of State Rex Tillerson also announced a new worldwide group Tuesday to increase the pressure on North Korea for a diplomatic solution to the global crisis over the regime's growing nuclear and ballistic missile programs. However, North Korea has set to flawless its re-entry technology.
The report said the testing involves ensuring anthrax survives the huge temperatures generated during re-entry into the Earth's atmosphere.