Summary of North Korea’s Nuclear Arsenal
May 31, 2005
by Madelyn Gee
It is difficult to accurately gauge North Korea’s nuclear arsenal. Based on intelligence reports of the quantity of plutonium they possess, it is reasonable to estimate they have as many as eight to eleven weapons. North Korea possesses operational short range and medium range missiles that could potentially be fitted with nuclear warheads in addition to bombers that may be converted to carry a nuclear payload.
North Korea declared its possession of a nuclear deterrent on Feb. 10, 2005, though the claim is difficult to confirm. Six-party disarmament talks, which include North and South Korea, Japan, China, Russia and the United States, have been deadlocked since the last talks in June 2004. In May 2005, U.S. intelligence officials detected increased activity and North Korea hinted that it would perform an underground test. The mystery surrounding Pyongyang’s nuclear program makes it particularly troubling, and it is unknown whether North Korea has operational warheads, how many may exist, and how many may be assembled. It is possible, however, to estimate how many nuclear weapons North Korea may have by tracking the quantity of fissile material and the estimated capabilities of the program.
North Korea’s nuclear program began with the creation of a nuclear energy research complex in Yongbyon in 1964, which included the Soviet IRT-2000 Nuclear Research Reactor. Over the next two decades, North Korea received technical assistance from the Soviet Union and China in constructing its nuclear infrastructure, and by the early 1970s, North Korean scientists had used indigenous technology to expand the research complex at Yongbyon in order to accommodate a large plutonium reprocessing plant using Soviet technology. The 20-megawatt thermal (MWt) reactor at Yongbyon began operation in 1986, a year after North Korea entered the Nuclear Non-Proliferation Treaty as a non-nuclear weapon state.
The Yongbyon complex is the center of North Korea’s plutonium capabilities, and in addition to the 20-MWt reactor, includes a fuel fabrication plant and a chemical separation (reprocessing) plant. North Korea ceased operation of this reactor following implementation of the 1994 Agreed Framework with the United States, but restarted the reactor and reprocessing plant in 2003 after withdrawing from the agreement in December 2002. North Korea had also suspended construction of a 200-MWt reactor in Yongbyon and a 700-800-MWt reactor near Taechon as part of the agreement, and there is no indication that North Korea has resumed construction of either reactor.
Less is known about North Korea’s uranium facilities than its plutonium capabilities. It is suspected that North Korea dealt extensively with Pakistani scientist and “father” of Pakistan’s bomb, Abdul Qadeer Khan, in the mid-1990s. Western intelligence analysts suspect that North Korea received uranium enrichment equipment and possibly even warhead designs in exchange for money and/or North Korean No-Dong missiles. However, it remains unknown whether any uranium program exists, and to what extent the technology may be developed.
North Korea is believed to have produced and recovered plutonium from the Yongbyon reactor at three distinct times. U.S. intelligence analysts believe that during a 70-day shutdown period in 1989, North Korea clandestinely removed fuel from the reactor and separated the plutonium. Different intelligence agencies differ on their estimate as to the amount of plutonium obtained. The U.S. State Department believes about 6-8 kg; the Central Intelligence Agency and Defense Intelligence Agency estimate 8-9 kg; the Institute for Science and International Security estimates as much as 14 kg; and international intelligence experts including South Korean, Japanese and Russian analysts posit a larger quantity ranging up to 24 kg. Between 1989 and 1993, North Korea produced an estimated 25-30 kg of plutonium, however it remained in spent fuel cells monitored under International Atomic Energy Agency (IAEA) safeguards until North Korea expelled inspectors in December 2002 and declared its intent to withdraw from the nuclear Non-Proliferation Treaty. During three-way talks with China and the United States in April 2003, a North Korean official claimed that most of the 8,000 spent fuel rods had been reprocessed. In April 2005, North Korea again shut down the Yongbyon reactor, possibly indicating the removal of additional spent fuel rods. On May 11, 2005, North Korean state-run media declared it had completed extraction of plutonium from the 8,000 fuel rods taken from its 5 MWt research reactor at Yongbyon. The Institute for Science and International Security estimates the remaining spent fuel rods would contain between 12 kg and 19 kg of plutonium. If indeed had North Korea completed removal of the plutonium from the remaining spent fuel rods in March, it would possess an estimated total of 43-57 kg weapons-grade plutonium.
Estimates of the number of nuclear weapons North Korea may possess are based on its estimated holdings of weapons-grade plutonium. The amount of plutonium or uranium necessary to build a bomb varies according to the desired yield and the warhead design, which depends on the technical capability of the scientists and engineers. Assuming a low technical capability would require more fissile material to produce a weapon and vice versa. The IAEA defines 8 kg of plutonium as the requisite amount for a nuclear weapon, however the Natural Resources Defense Council has estimated that a country with “high technical capability” could need as little as 1 kg of plutonium for a one kiloton bomb. Using the IAEA estimate of a requisite 8 kg of plutonium per weapon yields a possible North Korean capability of five to seven weapons. The Natural Resources Defense Council and Carnegie Endowment for International Peace both assume a medium technical capability is possible for North Korean scientists. Using the Carnegie Endowment’s requisite of 5 kg of plutonium per weapon yields a possible North Korean capability of eight to 11 weapons.
North Korea is among the more advanced of the late missile developing states, and maintains a large ballistic missile program including short-range and medium-range ballistic missiles. The No-Dong-1 is a medium-range ballistic missile that can range Japan and U.S. military bases in Okinawa. It was tested successfully in 1993. It is believed that North Korea has less than 50 of these missiles deployed. North Korea has also produced a large quantity of Scud B and Scud C missiles, many of which it has sold to other countries.
North Korea is known to be developing longer range ballistic missiles, including a variant of the No-Dong, and the Taepo-Dong, which analysts estimate could have a range greater than 6,200 km. Pyongyang test-fired the Taepo-Dong-1 in August 1998, launching the missile over Japan and into the Sea of Japan. North Korean officials claimed the launch was an attempt to place a satellite into orbit, however the third stage did not function properly and the satellite – if it existed – failed to reach orbit. While still under development, the untested two-stage and three-stage variants of the Taepo-Dong-2 may have a far greater range, if indeed they do exist.
It is unknown whether North Korea has sufficiently miniaturized any existing warheads enough to mount them on ballistic missiles.
North Korea maintains bomber and fighter aircraft that served nuclear strike roles in the Soviet Air Force. Theoretically these could be modified to carry a nuclear payload, though there is no evidence that any aircraft has been adapted for nuclear delivery.