Vinalon, the DPRK, and Chemical Weapons Precursors


An integral segment of the DPRK chemical industry is the production of vinalon, or "juche fiber." Of special significance is the fact that a number of North Korean defectors have linked Dr. Lee Sŭng Ki—the co-inventor of vinalon and father of polymer fiber production in the DPRK—with the DPRK chemical and nuclear weapons programs. It is also noteworthy that CW agent precursors for sulfur mustard could be readily supplied by North Korea's ample carbide production capability, the production of which is a preliminary step in the production of vinalon. It is quite possible, according to defectors, that the DPRK diverts significant quantities of raw material for making sulfur mustard agent and that there is ongoing chemical weapons production at vinalon manufacturing complexes in the DPRK.

    One day in February 1990, I was doing routine paper work at the staff operation office at around 10:00 o'clock in the morning when, to my surprise, the prison superintendent, vice-superintendent, intelligence chief, and three other unidentified officials walked into the room. One of them pointed to something outside my window. I was very terrified at their unusual appearance. Then, I overhead them saying, "Look! How powerful! What a great scientist Dr. Lee Sŭng Ki is, indeed! Well, from now on, its chemical warfare." I saw many prisoners lying on the slope of a hill, bleeding from their mouths and motionless, enveloped by strange fumes and surrounded by scores of guards in the gas masks I delivered to the Chief Guard earlier in the morning. Sun-ok Lee, former North Korean prisoner of the DPRK gulag.[1]

Vinalon Production in the DPRK: Source of Chemical Warfare Agent Precursors?

For many reasons, assessing the DPRK's capability in chemical warfare (CW) is exceedingly difficult. However, we can look at one significant facet of its chemical industry as a baseline departure for analysis and come away with some interesting information—and perhaps insight—into the DPRK strategy for CW agent production.

This integral segment of the DPRK chemical industry is the production of vinalon, or "juche fiber."[2] The synthetic process of creating this polymer merges two important ideological themes for North Korea: the heralded wisdom and promise associated with economic self-reliance (juche), and the purported uniqueness of those achievements. It is also significant that North Korean defectors have linked Dr. Lee Sŭng Ki—the co-inventor of vinalon and father of polymer fiber production in the DPRK—with the DPRK chemical and nuclear weapons programs.[3]

Vinalon and Possible Source of Precursors for Mustard Agent

In his testimony before the U.S. Congress, former Commander-in-Chief of the U.S. Forces in Korea General Thomas A. Schwartz assessed that the DPRK possesses "large chemical stockpiles and is self-sufficient in the production of chemical components for first generation chemical agents."[4] One agent that fits the description of a first-generation CW agent is sulfur mustard, a vesicant that was first used by Germany in 1917.

During World War I, Germany had diverted production of 2-chloroethanol to produce mustard, necessitating the manufacture of large quantities of alcohol. This could be done in a number of different ways. One method used ethylene and chlorination. This was then reacted with sulfur to form thiodiglycol, an immediate precursor to sulfur mustard:

It is noteworthy that CW agent precursors for sulfur mustard could be readily supplied by North Korea's ample carbide production capability. For the DPRK, having large deposits of anthracite coal and limestone, therefore, means ample supply of carbide. Furthermore, by mixing carbide with water, one can release and capture acetylene gas, the latter being only two hydrogen atoms away from ethylene. Ethylene is, of course, the starting point of many commercial products, such as plastics and detergents.

In the early years of the DPRK (1946-1950), using carbide to generate acetylene and then converting the latter to ethyl alcohol was of immediate interest to Dr. Lee Sŭng Ki, especially as a source for vinalon production.[5] This is because acetylene can be converted into vinyl acetate, and then into polyvinyl alcohol (PVA), which is later spun into vinalon fiber. The relevant point is that it is quite possible—even likely—that the DPRK diverts significant quantities of raw material (at the ethyl alcohol stage) for making sulfur mustard agent. That there is ongoing chemical weapons production (including blister agents like mustard) at vinalon manufacturing complexes in the DPRK is at least consistent with accounts from North Korean defectors.

With an endless source of raw material in the form of ethylene and the possibility that the DPRK has developed mustard agent as part of its chemical arsenal, the production capacity of sulfur mustard in North Korea is only limited by some intermediates such as hydrogen sulfide and hydrochloric acid. By all evidence, North Korea has substantial capabilities in producing these as well. With an estimated capacity of 50,000 tons of vinalon per year, the DPRK should have no shortage of chemical precursors for mustard agent manufacture. Although no data in the open literature can be found that suggest this has occurred—or is even likely—it is nonetheless possible that North Korea could provide chemical precursors for mustard agent or other toxic chemical compounds for terrorist groups or countries of proliferation concern.

History of Vinalon in the DPRK

As the DPRK media describe it, the fascinating story of vinalon begins with Lee Sŭng Ki, who was born in Tamyang, North Cholla Province in 1905. After graduating from Central Higher Normal School in Seoul, Lee Sŭng Ki left to study in Japan. There, he graduated from the Matsuyama Higher School—probably in 1931—and then matriculated into industrial science studies at Kyoto Imperial University, where he graduated as a chemical engineer. In 1939, working in a team led by professor Ichiro Sakurada, Lee Sŭng Ki and another Japanese colleague produced a water-insoluble fiber based on liquid PVA solution. (Lee Sŭng Ki was one of the three investigators credited with the patent in 1941.[6]) During roughly the same period, Kanegafuchi Spinning Co. published its results from using PVA and wet-spinning the polymer into fiber.[7] At that time, Japan was particularly well situated to produce PVA, as it then produced a large percentage of the world's calcium carbide.[8] This carbide production capacity allowed Japan to manufacture a nearly endless supply of precursor chemicals to manufacture PVA. [9]

By 1948, Japan had a large textile industry base, producing what it called "vinylon" from PVA-based fiber. This textile base was called "vinal" in the United States (although it was never produced in much quantity by American firms). By the time Lee Sŭng Ki had "defected" to North Korea in July 1950, the production of PVA and synthetic textiles using this polymer had already been well established.[10]

According to a Japanese-language account, Lee Sŭng Ki had spent several months in jail before being released following the end of Japanese occupation in 1945. His alleged crime was to have remarked to a Korean military policeman, using impolite language, that the "Japanese empire was doomed." Following World War II, Lee Sŭng Ki moved to Seoul as dean of engineering at Kyongsong University in November 1945 (today's Seoul National University, the top-ranked university in South Korea). About a week after the liberation of Seoul, one account has it that Lee Sŭng Ki met with Yi Chong-ok (d. 1999), who was later to become vice president of North Korea.

Yi Chong-ok had studied chemistry in China during its period of Japanese occupation. He, therefore, had become familiar with Lee Sŭng Ki's work. Yi Chong-ok had become manager of the Changjin Spinning Mill after the war. During a September 1947 on-the-spot guidance tour, Yi Chong-ok had recommended to Kim Il Sung that he invite Lee Sŭng Ki to the DPRK. It would require, however, the North's invasion of South Korea in June 1950 before Dr. Lee Sŭng Ki finally made his final trip to join the communist regime. (Lee Sŭng Ki almost certainly was not kidnapped and brought north against his will, as suggested in other histories.[11]) Upon his defection to the North, he was reported to have later reminisced, "I was surprised on the one hand, while very happy on the other. I was very happy that the Democratic People's Republic of Korea had succeeded in training in the short period of five years chemical plant technicians capable of producing alcohol from carbide. The reason is that that situation meant that a solid foundation had been established to proceed with research to industrialize vinalon, which I hoped to undertake thereafter."

In the DPRK, Dr. Lee conducted research on vinalon production "in a laboratory built in a great cave carved out of a mountain" in Chǒngsu-ri, Yanggang Province. Under spartan conditions and ensconced in a cave, the facility included such facilities as sleeping quarters, a dining room, bath, and recreation room. Despite wartime conditions, the cave was also supplied with "the equipment and reagents necessary for research." After the Korean War, sample vinalon products were initially produced in 1954 at the Chungsu chemical factory in Sakju, North Pyongyang province. Dr. Lee recounted the experience of vinalon in North Korea as follows:

I am not boastful of what I have done with vinalon. We did not suspend our research efforts even during the [Korean] war. We were also able to build a great vinalon factory via our own efforts. We designed and built the factory without assistance from foreign countries ...we are proud of our achievements. In the near future, we will probably record even greater achievements. It is critical that we embrace a spirit of independence.

Dr. Lee reportedly oversaw the first large manufacturing complex for vinalon in Hamhŭng City (in south Hamgyǒng Province). One history of Lee Sŭng Ki reports that Kim Il Sung attended the opening ceremony, and Lee also became director of the Institute for Chemistry at the Hamhŭng branch of the Academy of Science. Taking only about two years to complete its construction (from about 1959 through 1961), the manufacturing capacity of the February 8 Vinalon Complex was said to be 20,000 tons per year. The name and date of the complex is interesting for more than one reason. Kim Il Sung is said to have established the North Korean Provisional People's Committee (NKPPC) on February 8, 1946. It was therefore most fitting that Dr. Lee died on that same day and exactly 50 years later—February 8, 1996, according to a Japanese news account written by Korean residents in Japan sympathetic with the DPRK.[12] (For some reason, the coincidence of this date is not mentioned in North Korean retrospectives on Lee Sŭng Ki.[13])

Vinalon and Its Role in the North Korean Chemical Industry

As might be expected, the communist North developed industries that were in line with ideological expediency rather than being based on economic realities. For example, in the 1970s, Dr. Oh Kyǒng-ku, a recognized giant in DPRK chemical engineering, voiced his doubts about vinalon. He boldly (and unwisely) proclaimed that the "vinalon industry will not guarantee a future for light industry." This apostasy reportedly led to his being "struggled" for ideological revisionism—perhaps even by Kim Il Sung himself. Dr. Oh subsequently committed suicide in 1977.

A DPRK defector later described vinalon politics this way: "... [Vinalon] was a technology whose economy and efficiency were very suspect. However, given the fact that Kim Il Sung had already praised it and given direct orders [for its production], no one dared bring up the problems it involved." For another perspective, we can refer to Dr. Ma Kyong-sok, a South Korean leader in the chemical industry and a former student of Dr. Lee Sŭng Ki. With regard to vinalon, Dr. Ma opined the following: "North Korea is doomed. The reason for this is that it is pursuing a textile policy centered on vinalon, the production cost of which is excessively high." Still, despite the well-known drawbacks of the DPRK method of polymer production, Dr. Lee Sŭng Ki is still regarded as the "father of the North Korean chemical industry."[14]


It is certainly true that the DPRK has a very large production capacity for some raw materials and finished products. More salient to the North Korean experience, vinalon can be produced without significant foreign input, thus fulfilling the essence of juche. On a more practical level, vinalon has been used in North Korea and elsewhere in numerous products, including clothing, reinforcement of rubber, tarpaulin, fishing nets (particularly well suited due to its water resistance and physical properties), sewing thread, paper, bedding, filters, as well as films and resins. However, once produced in great quantity in the DPRK, Japan, China, and Russia, the widespread use of nylon and other synthetics has significantly reduced the overall market share for PVA fibers. Now, North Korea imports textiles from abroad, and reportedly utilizes nylon for making clothes, with some of this labor taking place in the North Korean gulag system. For example, the DPRK imported over one thousand tons of spun yarn annually during the 1990s.[15] Such reliance on imported materials not only demonstrates a lack of indigenous textile production, but also portends the ultimate failure of juche. Nonetheless, vinalon continues to be produced at the April 25 Vinalon Factory, the February 8th Vinalon Factory, and the Sŭnch'on Vinalon Complex, all suspected of producing mustard, as well as blood agents (e.g., cyanogen chloride), choking agents (phosgene), and riot-control agents (CN).



  • Nuclear Threat Initiative, North Korea Chemical Profile,
  • Federation of American Scientists, Vinalon, The North's Proud Invention,
  • Federation of American Scientists, North Korea, Chemical Weapons,
  •, Sunchon Vinalon Plant,
  • Center for Nonproliferation Studies, Monterey Institute, North Korea Special Collection,


[1] "Are They Telling Us the Truth? Summary and Analysis of the Following Five North Korean Witness Accounts on the Crimes against Humanity in North Korea," International Group of Human Rights Volunteers, Tokyo, Japan, March 2002.
[2] From Yi Chae Sung, Pukhanul Umjiginun Tek'unok'urat'u [Technocrats Who Move North Korea] (Seoul: Segye Ilbo, 1998) Chapter 3; translated in FBIS document FTS19991223001168.
[3] FBIS Report, "DPRK's Yi Sung-ki, Reputed 'Godfather of Chemical, Nuclear Weapons,' Profiled," April 25, 2001, in FBIS Document KPP20010425000114; Full Text of Q&A Note by Ex-DPRK Nuclear Re searcher, September 14, 2002, RENK WWW-Text, translated in FBIS Document JPP20021017000209, 17 October 2002.
[4] Thomas A. Schwartz, testimony before the Senate Armed Services Committee, "Testimony Fiscal 2002 Defense Authorization," March 27, 2001.
[5] Diagram of vinalon production found in Yi Chae Sung, Pukhanul Umjiginun Tek'unok'urat'u [Technocrats Who Move North Korea], (Seoul: Segye Ilbo, 1998), p. 127.
[6] Patent no. 147,958, February 20, 1941, Ichiro Sakurada, Yi Sung-ki [Lee. S.] and H. Kawakami, issued to Institute of Japan Chemical Fiber. Jun-Ichi Hikasa, "Poly(Vinyl Alcohol)," in Kirk-Othmer, Encyclopedia of Chemical Technology, fourth edition, Vol. 10 (New York: John Wiley & Sons, 1992) pp. 685-696.
[7] Jun-Ichi Hikasa, "Poly(Vinyl Alcohol)," in Kirk-Othmer, Encyclopedia of Chemical Technology, fourth edition, Vol. 10 (New York: John Wiley & Sons, 1992) pp. 685-696.
[8] In 1891, Major James Morehead and Thomas Willson developed a process to produce calcium carbide by heating coal and limestone to very high temperatures. When mixed with water, calcium carbide liberates acetylene gas (C2H2). Having developed an economically viable process for continuous production of carbide through with a special furnace, the Union Carbide Company was formed in 1898. Being able to produce acetylene via carbide held great promise, for this is a gas that not only could be used in public street lamps, high-temperature welding, and other applications, but can also spin off a number of organic chemical derivatives.
[9] K. Noro, "Manufacture of Polyvinyl Acetate for Polyvinyl Alcohol," in C.A. Finch, ed., Polyvinyl Alcohol: Properties and Applications (New York: John Wiley & Sons, 1973) p. 67.
[10] "'Vinalon,' the North's proud invention," 2001, South Korean National Intelligence Service, Dr. Lee Sung-ki has been described having "traveled" or "defected" to the North in various sources. Because he found himself in North Korea after the June 1950 invasion, it is likely that some defection had occurred.
[11] This is suggested by the following account: "[After World War II,] Kim Il-song came into power. During the Korean War of 1950, he ordered Yi Hak-mun, the Yi Chung republic reconnaissance hero, to abduct Dr. Lee Sung-ki, Dr. To Won-son, researcher To Sang-nok, and other people from South Korea, and to be brought into North Korea for the purpose of developing nuclear arms." Full Text of Q&A Note by Ex-DPRK Nuclear Re searcher, September 14, 2002, RENK WWW-Text, translated in FBIS Document JPP20021017000209, October 17, 2002.
[12] "DPRK Pioneer Scientist Yi Sung-ki Profiled," translation from Gendai Chosen no Kagakushatachi, a book written about North Korean personages in science, 16 February 1997, pp. 8-19, in FBIS Document KPP20020925000101.
[13]"Yi Chong-ok to Lead Funeral Committee for Yi Sung-ki," KCNA, February 9, 1996, transcribed in FBIS Document SK0902052096.
[14] Pak Ch'an-mo, "Global Reputation of Dr. Lee Sung-ki, Inventor of Vinalon,"Kwahak-kwa Kisul, March 26-27, 2001, translated in FBIS Document KPP20020503000095.
[15] Financial Express, May 13, 1997, p. 8.

February 1, 2003

Eric Crodder investigates the possible bridge between North Korean Vinalon production and its chemical weapons program.

Eric Croddy

Senior Research Associate, CBW Nonproliferation Program

This material is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies at Monterey and does not necessarily reflect the opinions of and has not been independently verified by NTI or its directors, officers, employees, or agents. Copyright 2018.