The reported discovery of anthrax antibodies in a North Korean defector is renewing fears that the regime of Kim Jong Un is developing lethal biological weapons in violation of international law.

A South Korean intelligence officer told that nation's Channel A television that one of at least four soldiers who defected from the North this year had the antibodies in his system. Senior defense analyst Shin Jong Woo said the anthrax vaccine is probably given to North Korean soldiers working on biological weapons projects.

Although rare in the United States, people can get sick with anthrax if they come in contact with infected animals or contaminated animal products, according to the Centers for Disease Control and Prevention website. Contact with anthrax can cause severe illness and death if not treated, according to the CDC, which noted that anthrax is not contagious like a common cold or flu.

The revelation about the defector comes a week after reports began circulating that North Korea had begun tests to load anthrax onto intercontinental ballistic missiles. The Japanese newspaper Asahi Shimbun, citing intelligence sources in Seoul, has reported that Kim's regime is conducting heat and pressure resistance tests to see whether anthrax germs can survive the intense heat an intercontinental ballistic missile encounters when it re-enters Earth’s atmosphere.

North Korea has denied it is developing chemical weapons, something it has been accused of doing in the past.

The U.S. National Security Strategy released last week by the Trump administration accuses North Korea of conducting research into "chemical and biological weapons" that could be delivered by missile.

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North Korea has been accused of using chemical weapons on a smaller scale. Kim Jong Nam, North Korean leader Kim Jong Un's older half-brother and a potential rival, was killed in an attack with a deadly nerve agent at Malaysia's international airport in February.

The government imported 350 doses of anthrax vaccine Nov. 2 and stored them in a national army hospital. The Korea Centers for Disease Control and Prevention has enough anthrax vaccine for 1,000 patients in case of biological terror attacks, the government said.

The heightened concerns about anthrax come six weeks before South Korea hosts the 2018 Winter Olympics.

Sanctions and bellicose rhetoric continue to dominate U.S.-North Korean relations. Last week, the United Nations imposed another round of sanctions on North Korea in reaction to the country's repeated testing of intercontinental ballistic missiles, including the first one with a range that can reach Washington, D.C.

Kim says his goal is to develop a nuclear-armed missile that can hit the U.S. as a deterrent against an American invasion seeking to overthrow him.

The latest U.N. resolution, which even drew support from North Korean benefactors China and Russia, limits 90% of petroleum exports to North Korea and demands that North Koreans working abroad for Kim's regime return home. Sixteen North Korean officials, mostly in the banking sector, were added to the sanctions blacklist along with the ministry that manages the logistics of its armed forces.

Kim's government was unmoved. Its Foreign Ministry issued a statement condemning the resolution as "an act of war."

"The United States, completely terrified at our accomplishment of the great historic cause of completing the state nuclear force, is getting more and more frenzied in the moves to impose the harshest-ever sanctions and pressure on our country," the ministry statement said.

Corrections & Clarifications: A previous version of this article misidentified South Korea's president.