Fears that Pyongyang might unleash a biological terror attack have added another layer of tension on the Korean Peninsula, but security analysts say that North Korea has probably backed away from the mass weaponization of lethal agents due to reliability issues.

The threat has not passed, however, as the hardline state has lots of low-tech delivery systems at its disposal.

There is little documented evidence of North Korea’s stockpiling of biological agents, but US and South Korean intelligence agencies believe it began in the late 1960s, and that they were likely weaponized in the 1980s.

Although it acceded to the Biological Weapons Convention in March 1987, Pyongyang has continued to recruit scientists, import technologies — usually under the guise of conventional research in civilian fields like agriculture and medicine — and source precursors. It has had little active involvement in the convention and does not permit foreign monitoring.

At least a dozen facilities appear to be capable of either supplying biological agents or adapting them for military use, but South Korea’s Ministry of National Defense (MoND) said in 2001 most activity occurred at three plants and six research centers, some with dual civilian-military usage.

Key facilities are the Central Biological Weapons Research Institute in Pyongyang; the No 25 (25 February) germs production plant in Chongju, North Pyongan Province; a research center near the Onjong-ni chemical weapons plant in Songchon County, South Pyongan Province; and the Research Institute of the Armed Forces Ministry. The latter, which works in conjunction with the Bacterium Research Institute at the Second Academy of Natural Sciences, is responsible for developing biological weapons.

According to the Federation of American Scientists (FAS), research into disease pathogens like bubonic plague, anthrax, yellow fever and cholera is also conducted at the National Defense Research Institute and Medical Academy. Civilian medical facilities, including Kim Il-sung University, the Pyongyang Medical College, and the Institute of Microbiological Diseases at Pyongsong Academy of Science, routinely contribute to the research base.

It is difficult to get accurate data on the scale of the program, but South Korea has said that just one production plant, at Munchon in Kangwon Province, supplies about 200 tons of germ growth media each year.

Studies by the Nuclear Threat Initiative indicate North Korea has already developed or is researching toxins and viral and bacterial biological agents, including pathogens for plague, typhoid, yellow fever, anthrax, botulism, cholera, smallpox, dysentery and yellow rain T-2 micro toxins.

North Korea has stated in five public reports since 2002 that it has 13 types of agents, and the “capability to cultivate and weaponize them.”

‘Missiles, artillery adapted for bio-weapons’

South Korea’s MoND said in an April 2012 report that 50% of the North’s long-range missiles and 30% of its artillery had been adapted to carry either biological or chemical weapons; the weapons could also be deployed via rocket launchers, mortars and field artillery. It concluded that agents for botulism, smallpox and anthrax were mostly likely to be weaponized.

But having a weapons capability is only half of the battle with biological agents, which need to be stabilized so they will survive long enough to be effectively dispersed. Toxins aside, these are living organisms, making them sensitive to temperature change, varying pressure and other factors.

One method of deployment is via a warhead. Like any weapons system, biological warheads need to be tested to check payloads, measure the impact of rapid acceleration and vibrations, and verify the reliability of fuzes, detonators and ejection mechanisms. North Korea is said to have tested pathogens on prisoners and disabled children – defectors have related horrific stories of human guinea pigs in camps – but has not conducted any live firing of projectiles to test their reliability.

“Biological warfare has not received the same attention as chemical or nuclear warfare. This could be because North Korea lacks the technical expertise or because the difficulty in controlling biological warfare makes it a less desirable option,” the FAS reported.

‘Just as dangerous to its own forces’

Moreover, South Korea has an advanced national medical system, whereas the North does not, which means any blowback on the North could be more devastating than on the original target, the South.

“North Korea realizes that biological weapons are as dangerous to its own forces as they are to South Korean or US forces, and the North’s limited medical services would make the agents more lethal. Therefore, using biological agents is not a likely option,” the FAS noted.

Recent analysis by US intelligence agencies also lowered the threat level for large-scale military deployment of biological weapons, but did not rule out other uses, such as assassinations.

North Korea seems to have few qualms about deploying weapons of mass destruction even in public, international spaces. It allegedly employed a chemical weapon, VX nerve agent, to murder Kim Jong-nam, the half-brother of Kim Jong-un, in a brazen attack in Malaysia’s Kuala Lumpur airport. The method used – rubbing the highly toxic chemical on Kim’s face — was basic, but effective. He was dead within minutes.

Assessments by Global Security indicate that aerosol dissemination by pressurized gases, the method used by a now-redundant US program, would be the easiest way to use bio-weapons. Aerosols deployed from aircraft can achieve a dissemination efficiency of up to 60%, compared with less than 1.5% for biological agents delivered through explosive devices.

Spraying bio-agents in a closed space – such as a crowded subway system – would be even more effective. In 1985 the shadowy Aum Shinrikyo cult killed 12 people and badly injured 50 others when it released the nerve agent sarin on three Tokyo rail lines. Ten grams of anthrax spores, believed to be one of North Korea’s preferred agents, could kill as many people as one ton of sarin.

An October report by Harvard Kennedy School’s Belfer Center for Science and International Studies suggested that Pyongyang might deploy biological weapons from aerosols mounted on drones. A number of unarmed drones have already been found, crashed, in South Korea.

The Belfer Center also floated the ultimate security nightmare: the use of human vectors.

“North Korea has 200,000 special forces; even a handful of those special forces armed with BW [biological weapons] would be enough to devastate South Korea,” the report said, listing water and foodstuffs as likely targets.

Spraying a water reservoir could kill tens of thousands if it could be targeted efficiently. The assailant would probably die too, but the Belfer Center noted this was unlikely to bother a society with a history of “prioritizing military objectives over human lives.”