North Korea’s progress toward developing a nuclear arsenal capable of targeting opponents as far away as the United States has long been a subject of concern for American defense officials.  Few weapons in history can illicit such a sense of dread and foreboding, but with the potential for conflict on the Korean Peninsula reaching new highs, there are other weapons that deserve similar levels of concern: North Korea’s chemical and biological stockpiles.

The assassination of Kim Jong-un’s half-brother, and early favorite to lead the nation, Kim Jong Nam, not only provided us with insight into the mind of North Korea’s Supreme Leader, but served as a reminder of North Korea’s secretive chemical and biological weapons programs.  VX, the chemical identified as the weapon used to murder Kim Jong Nam, is widely considered to be difficult enough to produce to require state-level backing of the laboratory that made it, and multiple North Korean operatives were implicated in the assassination.  Of course, North Korea still publicly rejects the notion that their government was involved, meanwhile everyone tied to the plot with North Korean roots managed to escape Malaysia and prosecution.

The use of VX to kill Kim Jong Nam by North Korea, while publicly refuted, could be seen as a message intended for the world at large.  Prior to this incident, there was no hard evidence to support the idea that Kim’s regime has been developing and stockpiling these forms of weapons, considered illegal by the international community.  Like the radioactive isotope, polonium 210, that killed Alexander Litvinenko tied his murder to the Kremlin in a way Putin was able to deny, the use of VX to kill Kim Jong Un’s brother was also meant as a very public, and very worrisome, statement.

“North Korea has deliberately built its NBC [nuclear, biological, chemical] infrastructures in extreme secrecy; undertaken camouflage, concealment and deception operations . . . and dispersed NBC facilities around the country,” Joseph S. Bermudez Jr., a prominent expert on North Korean weapons systems, wrote in a joint report released by Johns Hopkins School of Advanced International Studies and the U.S. Korea Institute last month.

“It is therefore probable that there are significant elements of the NBC programs and their infrastructures that are simply unknown outside the North Korean government.”

The idea that North Korea could potentially use chemical or biological agents against America and its allies isn’t a foreign one for U.S. commanders in South Korea.  Both countries’ militaries inoculate their troops against exposure to anthrax bacteria and the smallpox virus when stationed along the border.  Drills are conducted along the border with some regularity, intended to prepare American and South Korean troops for the day canisters of sarin or VX gas begin flying over the DMZ.

North Korea did not sign the international Chemical Weapons Convention, meaning by their own standards, the production and use of weapons like VX or sarin may not seem illegal – though they clearly appreciate how the international community would respond if their weapon stockpiles became public knowledge.

According to a South Korean defense report, it is believed Kim may already have as many as 5,000 tons of chemical weapons stored, in the form of 25 different agents, including sarin, mustard, tabun and hydrogen cyanide.  Nerve agents are also assumed to be stockpiled, such as the VX used to assassinate Kim Jong Nam.  Biological agents believed to be stockpiled include anthrax, smallpox, and even the plague.  If true, this would mean Kim Jong Un possesses one of the world’s largest stockpiles of chemical and biological weapons.