A North Korean soldier who defected to South Korea was found to have antibodies to anthrax, Tuesday reports said.

It is not clear which defector was found to have anthrax, but it is widely believed to be the unidentified soldier who defected in November.

Without antibiotics or a vaccination, anthrax has a mortality rate of 80% within 24 hours.

According to South Korean Defense Ministry spokeswoman Choi Hyun-soo, an anthrax vaccine may be developed by the end of 2019, "but not sooner," UPI reported.

According to Japan's Asahi, North Korea arms intercontinental ballistic missiles (ICBM) capable of reaching the US with anthrax, and the US is testing whether anthrax can survive re-entry into the Earth's atmosphere.

A White House report earlier this month noted that North Korea is "pursuing chemical and biological weapons" which can be delivered "by missile."

Meanwhile, North Korea denied the accusation, threatening to take "revenge" on the US for claiming the country is developing biological weapons.

According to a statement from the Korean Central News Agency, the more the US insists on its anti-North Korea stance, the "more hardened the determination of our entire military personnel and people to take revenge will be."

On Tuesday, the US announced sanctions on two North Korean officials behind their country’s ballistic missile program.

Last week, The Telegraph reported that the US is drawing up plans for an attack on North Korea. However, this report was not confirmed by the US government,