North Korea's Nuclear Weapons: Latest Developments

Prepared for Members and Committees of Congress

This report summarizes what is known from open sources about the North Korean nuclear
weapons program—including weapons-usable fissile material and warhead estimates—and
assesses current developments in verifying dismantlement of North Korea’s nuclear facilities as
agreed in the Six-Party Talks. The Six-Party Talks include the United States, South Korea, Japan,
China, Russia, and North Korea, and were begun in August 2003 to attempt to resolve the current
crisis over North Korean nuclear weapons.
Beginning in late 2002, North Korea ended an eight-year freeze on its plutonium production
program, expelled international inspectors, and restarted facilities. North Korea may have
produced enough additional plutonium for five nuclear warheads since 2002. In total, it is
estimated that North Korea has up to 50 kilograms of separated plutonium, enough for at least
half a dozen nuclear weapons. On February 10, 2005, North Korea announced that it had
manufactured nuclear weapons for self-defense and that it would bolster its nuclear weapons
arsenal. On October 9, 2006, North Korea conducted a nuclear test, with a yield of under 1
kiloton. The United States and other countries condemned the test, and the United Nations
Security Council passed Resolution 1718 on October 14, 2006, that requires North Korea to (1)
refrain from nuclear or missile tests, (2) rejoin the Nuclear Nonproliferation Treaty (NPT), and
(3) abandon its weapons of mass destruction and ballistic missile programs.
On February 13, 2007, North Korea reached an agreement with other members of the Six-Party
Talks to begin the initial phase (60 days) of implementing the Joint Statement from September
2005 on denuclearization. Key components of the agreement include halting production at the
Yongbyon nuclear complex and delivery of heavy fuel oil to North Korea. In July 2007,
International Atomic Energy Agency (IAEA) inspectors verified the shutdown of the Yongbyon
facilities. On October 3, 2007, the Six Parties adopted a Joint Statement in which North Korea
agreed to disable the Yongbyon facilities and provide a declaration of all its nuclear programs by
December 31, 2007. The October 2007 statement said the United States would lead disablement
activities and provide the initial funding for those activities.
Much still remains to be confirmed regarding North Korea’s nuclear weapons production
capabilities and delivery systems, particularly regarding uranium enrichment. Although U.S.
officials confronted the North Koreans in 2002 with intelligence that reportedly proved that
Pyongyang was pursuing a uranium enrichment program, U.S. intelligence officials have said
they do not know where the uranium program is based and have over time shown less confidence
about what the scope of the program might be. Further, although seismographs registered the
October 9, 2006, detonation and environmental sampling confirmed radioactivity, uncertainty
about the weapon’s design and sophistication remains. Additional transparency on fissile material
stocks and programs, including the uranium enrichment program, may contribute to a better
picture of North Korean nuclear weapons capabilities. This report will be updated as events

Backgr ound ..................................................................................................................................... 1
Weapons Production Milestones.....................................................................................................2
Verification and “Disablement”.......................................................................................................3
Declar ation .................................................................................................................... ............ 3
Disabl ement............................................................................................................................... 4
Verification ................................................................................................................... ............. 5
The October 9, 2006, Nuclear Test..................................................................................................6
Estimating Nuclear Warheads and Stocks.......................................................................................7
Plutonium Production......................................................................................................................8
A Uranium Enrichment Program?...................................................................................................9
Delivery Systems...........................................................................................................................12
Doctrine and Intent........................................................................................................................12
Issues for Congress........................................................................................................................13
Author Contact Information..........................................................................................................14

In the early 1980s, U.S. satellites tracked a growing indigenous nuclear program in North Korea.
The North Korean nuclear program began in the late 1950s with cooperation agreements with the
Soviet Union on a nuclear research program near Yongbyon. Its first research reactor began
operation in 1967. North Korea used indigenous expertise and foreign procurements to build a
small nuclear reactor at Yongbyon (5MWe). It was capable of producing about 6 kilograms (Kg) 1
of plutonium per year and began operating in 1986. Later that year, U.S. satellites detected high
explosives testing and a new plant to separate plutonium. In addition, construction of two larger
reactors (50MWe at Yongbyon and 200MWe at Taechon) added evidence of a serious clandestine
effort. Although North Korea had joined the Nuclear Nonproliferation Treaty (NPT) in 1985
under Soviet pressure, safeguards inspections began only in 1992, raising questions about how
much plutonium North Korea had produced covertly. In 1994, North Korea pledged, under the
Agreed Framework with the United States, to freeze its plutonium programs and eventually 2
dismantle them in return for several kinds of assistance. At that time, western intelligence
agencies estimated that North Korea had separated enough plutonium for one or two bombs; other
sources estimated four to five bombs. North Korea complied with the Agreed Framework,
allowing International Atomic Energy Agency (IAEA) seals—including the “canning” of spent
fuel rods at the Yongbyon reactor—and permanent remote monitoring and inspectors at its
nuclear facilities.
When in 2002, U.S. negotiators reportedly presented North Korean officials with evidence of a
clandestine uranium enrichment program, the North Korean officials reportedly at first confirmed
this, then denied it publicly. The conflict quickly led to the breakdown of the Agreed Framework.
The Bush Administration argued that North Korea was in “material breach” of its obligations and,
after agreement with South Korea, Japan, and the EU (the other members of the Korean 3
Economic Development Organization, or KEDO), stopped the next shipment of heavy fuel oil.
In response, North Korea kicked out international monitors, broke the seals at the Yongbyon
nuclear complex, and restarted its reactor and reprocessing plant after an eight-year freeze.
Members of the Six-Party Talks—the United States, South Korea, Japan, China, Russia, and
North Korea—began meeting in August 2003 to try and resolve the crisis. In September 2005, the
Six Parties issued a Joint Statement on how to achieve verifiable denuclearization of the Korean 4
Peninsula, which formed the basis for future agreements. After negotiations broke down, North
Korea tested a nuclear device in October 2006. The Denuclearization Action Plan of February 5
2007 called for shut-down of facilities and provision of fuel oil to North Korea. Currently in the
second phase of this plan, the United States is working with North Korea to disable key facilities.

1 5MWe is a power rating for the reactor, indicating that it produces 5 million watts of electricity per day (very small).
Reactors are also described in terms of million watts of heat (MW thermal).
2 See CRS Report RL33590, North Koreas Nuclear Weapons Development and Diplomacy, by Larry A. Niksch.
3 “Adherence To and Compliance With Arms Control, Nonproliferation and Disarmament Agreements and
Commitments, U.S. Department of State, August 2005.
4Joint Statement of the Fourth Round of the Six-Party Talks, Beijing, September 19, 2005, at
5 The United States authorized its first shipment of 50,000 metric tons of heavy fuel oil to North Korea in September
2007. Peter Baker, “U.S. to Ship Fuel Oil to North Korea,The Washington Post, September 29, 2007.

North Korea has not yet submitted a declaration of its nuclear program that was due at the end of 6

2007, as promised in an October 3, 2007, joint statement on “Second-Phase Actions.”

The Denuclearization Action Plan does not include actions that will address fissile material
stocks, the uranium enrichment program, or dismantlement of warheads and instead focuses on
shutting down and disabling, for at least a year’s time, the key plutonium production facilities. A
third phase, to begin after disablement is complete and a declaration is accepted by the Six
Parties, is supposed to address all aspects of North Korea’s nuclear program, including weapons,
using North Korea’s declaration as a basis for future action. Understanding the scope of the
program and the weapons capability will require transparency and careful verification for
“complete, verifiable, irreversible” disarmament to be achieved.

Acquiring fissile material—plutonium-239 or highly enriched uranium (HEU)—is the key hurdle 7
in nuclear weapons development. Producing these two materials is technically challenging; in 8
comparison, many experts believe weaponization to be relatively easy. North Korea has
industrial-scale uranium mining and plants for milling, refining, and converting uranium; it also
has a fuel fabrication plant, a nuclear reactor, and a reprocessing plant—in short, everything
needed to produce Pu-239. In its nuclear reactor, North Korea uses magnox fuel—natural
uranium (>99%U-238) metal, wrapped in magnesium-alloy cladding. About 8,000 fuel rods
constitute a fuel core for the reactor.
When irradiated in a reactor, natural uranium fuel absorbs a neutron and then decays into
plutonium (Pu-239). Fuel that remains in the reactor for a long time becomes contaminated by the 9
isotope Pu-240, which can “poison” the functioning of a nuclear weapon. Spent or irradiated
fuel, which poses radiological hazards, must cool after removal from the reactor. The cooling
phase, estimated by some at five months, is proportional to the fuel burn-up. Reprocessing to
separate plutonium from waste products and uranium is the next step. North Korea uses a PUREX
separation process, like the United States. After shearing off the fuel cladding, the fuel is
dissolved in nitric acid. Components (plutonium, uranium, waste) of the fuel are separated into
different streams using organic solvents. In small quantities, separation can be done in hot cells, 10
but larger quantities require significant shielding to prevent deadly exposure to radiation.
North Korea appears to have mastered the engineering requirements of plutonium production. It
has operated its nuclear reactor, is believed to have separated Pu from the spent fuel, and has
reportedly taken steps toward weaponization. In January 2004, North Korean officials showed an

6 Second-Phase Actions for the Implementation of the September 2005 Joint Statement, October 3, 2007
7 Highly enriched uranium (HEU) has 20% or more U-235 isotope; 90% U-235 is weapons-grade.
8 The physical principles of weaponization are well-known, but producing a weapon with high reliability, effectiveness,
and efficiency without testing presents significant challenges.
9 Plutonium that stays in a reactor for a long time (reactor-grade, with high “burn-up”) contains about 20% Pu-240;
weapons-grade plutonium contains less than 7% Pu-240.
10 Hot cells are heavily shielded rooms with remote handling equipment for working with irradiated materials. For
background, see Jared S. Dreicer, “How Much Plutonium Could Have Been Produced in the DPRK IRT
Reactor?”Science and Global Security, 2000, vol. 8, pp. 273-286, at

unofficial U.S. delegation alloyed “scrap” from a plutonium (Pu) casting operation.11 Dr.
Siegfried Hecker, a delegation member, assessed that the stated density of the material was
consistent with plutonium alloyed with gallium or aluminum. If so, this could indicate a degree of
sophistication in North Korea’s handling of Pu metal, necessary for weapons production. But
without testing the material, Hecker could not confirm that the metal was plutonium or that it was
alloyed, or when it was produced.

In September 2005, North Korea agreed to abandon “all nuclear weapons and existing nuclear 12
programs,” but implementation of this goal was stalled. The October 9, 2006, nuclear test is
seen as a catalyst in uniting the other members of the Six Party Talks to toughen their stance
towards North Korea, and as a turning point in Pyongyang’s attitude. UN Security Council
Resolution 1718 calls on North Korea to abandon its nuclear weapons in a “complete, verifiable, 13
and irreversible manner.” In February 2007, as part of implementation of the September 2005
Joint Statement, North Korea committed to disable all nuclear facilities and provide a “complete 14
and correct” declaration of all its nuclear programs by December 31, 2007.
The Bush administration expects the declaration to include a full declaration of the separated
weapons-grade plutonium that has already been produced, as well as full disclosure of uranium 15
enrichment activities. As of mid-January 2008, North Korea had not yet submitted a declaration.
North Korean Foreign Ministry said on January 4 that it had notified the United States of the
content of its declaration in November 2007. However, Assistant Secretary Hill said that the two
sides had discussed what was expected to be in a declaration, and “it was clearly not a complete 16
and correct declaration.” North Korea reportedly suggested it would declare 30 kg of separated
plutonium in its declaration, a lower number than U.S. officials have alluded to (see above) but in 17
the range of some analyses. The United States has said that “materials, facilities and programs”
need to be included in a declaration. In addition to plutonium stocks, North Korea has agreed to
“address concerns about a uranium enrichment program but denies that it has one (see below).

11 Alloying plutonium with other materials iscommon in plutonium metallurgy to retain the delta-phase of plutonium,
which makes it easier to cast and shape (two steps in weapons production). Hecker, January 21, 2004, testimony
before SFRC.
12 Joint Statement of the Fourth Round of Six Party Talks, Beijing, September 19, 2005, at
13 United Nations Security Council Resolution 1718, October 14, 2006, at
14Denuclearization Action Plan,” February 13, 2007, at
15 On-The-Record Briefing: Assistant Secretary of State for East Asian and Pacific Affairs and Head of the U.S.
Delegation to the Six-Party Talks Christopher R. Hill, October 3, 2007, at
16 Joint Press Availability, Assistant Secretary of State Christopher R. Hill, January 7, 2008.
17 David Albright, Paul Brannan, and Jacqueline Shire,North Koreas Plutonium Declaration: A Starting Point for an
Initial Verification Process,” The Institute for Science and International Security, January 10, 2008. http://www.isis-

Other outstanding issues are nuclear proliferation activities and warhead information.18 North
Korea has said it would not include warhead information at this stage. Since December 31, when
expectations that North Korea would provide a declaration were not met, U.S. officials have
emphasized that the completeness of the document is more important than its timing. Ambassador
Chris Hill suggested that it would be preferable to have a declaration from the North Koreans 19
before the end of February, when the new South Korean president takes office. North Korea also
has expressed dissatisfaction that the United States has not yet removed it from the Terrorism List
or lifted the Trading with the Enemy Act sanctions, both part of Phase 2. U.S. officials in
response have made clear that these actions would be taken only after a complete declaration is
submitted to the six parties.
The October 2007 joint statement said the United States would lead disablement activities and 20
provide the initial funding for those activities. Disablement indicates a physical measure to
make it difficult to restart operation of a facility while terms are being worked out for its eventual
dismantlement. U.S. officials have said that they would prefer a disablement process that would 21
require a 12-month time period to start up the facility again. A team of U.S. technical experts in
mid-October 2007 continued negotiations with the North Koreans on a plan that reportedly
includes 10 discrete steps to disable the three main Yongbyon facilities related to North Korea’s
plutonium program (nuclear fuel fabrication plant, plutonium reprocessing plant, and 5-megawatt 22
experimental nuclear power reactor). The step that requires the most time to achieve will be the 23
remove of the irradiated fuel from the reactor to storage in an adjacent cooling pond. The 24
disablement process began in early November 2007. Japan has reportedly also expressed 25
interest in contributing expertise, but it is not clear if this will be agreed to by North Korea.
On January 4, 2008, North Korea announced that it would slow the pace of disablement (at this
stage meaning removal of fuel rods), in response to stalemate over the contents of a declaration
and in response to fuel shipments not having been received on time and the United States not yet 26
removing it from the terrorism list. Nevertheless, U.S. officials report that significant progress
has been made, and said that a slowing of fuel rod removal was necessary for safety reasons. A
South Korean official said that fuel rod removal is expected to take several months, and may be 27
completed by the end of March.

18 See CRS Report RL33590, North Koreas Nuclear Weapons Development and Diplomacy, by Larry A. Niksch for a
detailed treatment.
19 Press Conference at Incheon Airport, January 10, 2008, at
20 Second Phase Actions for the Implementation of the September 2005 Joint Statement, October 3, 2007, at
21 On-the-Record-Briefing, U.S. Assistant Secretary of State Christopher Hill, October 3, 2007, at
22 “North Korea ‘Agrees to Nuclear Disablement Procedure,’” Chosun Ilbo, October 27, 2007.
23 David Albright and Paul Brannan, “Disabling DPRK Nuclear Facilities,” United States Institute of Peace Working
Paper, October 23, 2007.
24 “U.S. Team heads to N.K. to begin nuclear disablement,Yonhap English News, October 31, 2007.
25 Japan Eyes Support for Disabling N. Korea Nuke Facilities,” Jiji Press English News Service, October 29, 2007.
26N.Korea ‘Slowing Disablement of Nuclear Facilities,” Chosun Ilbo, January 29, 2008.
27 “North Korea Completes Eight Disablement Measures, Associated Press, February 1, 2008.

IAEA inspectors returned to North Korea in July 2007 to monitor and verify the shut-down,
install seals, and monitor facilities at the Yongbyon nuclear complex, and have had a continuous 28
presence there since then. In his September 10, 2007, statement to the IAEA Board of
Governors, Director General Mohamed ElBaradei stated that the IAEA was able to verify the
shutdown of nuclear facilities, including the nuclear fuel fabrication plant, radio-chemical
laboratory (reprocessing plant), and the 5MWe experimental nuclear power reactor. Inspectors are
also monitoring the halt in construction of the 50-megawatt nuclear power plant at Yongbyon and 29
the 200-megawatt nuclear power plant in Taechon. The United States has contributed $1.8
million as the U.S. voluntary contribution and Japan has contributed $500,000 to the IAEA for 30
their work in North Korea. In the future, the IAEA may be called on to investigate North
Korea’s past nuclear program in addition to monitoring activities; however, to date, its role has
been limited to monitoring the shut-down of Yongbyon facilities. The IAEA’s role in disablement
and future dismantlement efforts has yet to be determined. Some analysts recommend an observer
role for the IAEA during disablement steps and continued IAEA monitoring to boost international 31
confidence in the process.
Since IAEA inspectors were expelled from North Korea in 2002, information about North
Korea’s nuclear weapons production has depended on remote monitoring and defector
information, with mixed results. Satellite images correctly indicated the start-up of the 5MWe
reactor, but gave no details about its operations. Satellites also detected trucks at Yongbyon in late 32
January 2003, but could not confirm the movement of spent fuel to the reprocessing plant;
imagery reportedly detected activity at the reprocessing plant in April 2003, but could not confirm 33
large-scale reprocessing; and satellite imagery could not peer into an empty spent fuel pond,
which was shown to U.S. visitors in January 2004. North Korean officials stated in 2004 that the
reprocessing campaign was conducted continuously (four six-hour shifts). U.S. efforts to detect
Krypton-85 (a by-product of reprocessing) reportedly suggested that some reprocessing had taken
place, but were largely inconclusive. Even U.S. scientists visiting Pyongyang in January 2004
could not confirm North Korean claims of having reprocessed the spent fuel or that the material
shown was in fact plutonium. Verifying those claims will require greater access to the material
and North Korean cooperation, and it is hoped that significant progress will be made on these
issues in 2008, after North Korean submits a declaration detailing its nuclear program.
The next stage of verification, after disablement, will be the decommissioning and dismantlement
of the weapons production facilities. The terms for this work still need to be negotiated. This

28IAEA Team Confirms Shut Down of DPRK Nuclear Facilities,” IAEA press release, July 18, 2007,a t
29 GOV/2007/45-GC(51)/19, August 17, 2007.
30 Statement of Christopher R. Hill Assistant Secretary, Bureau of East Asian and Pacific Affairs, Department of State
before the House Committee on Foreign Affairs, Subcommittee on Asia, the Pacific and the Global Environment and
Subcommittee on Terrorism, Nonproliferation and Trade, Joint Hearing on the North Korea Six-Party Process, October
25, 2007.
31 North Korea reportedly did not want the IAEA involved and wanted the United States to do the disabling. Albright
and Brannan, ibid.
32 “Reactor Restarted, North Korea Says, Washington Post, February 6, 2003.
“US Suspects North Korea Moved Ahead on Weapons,New York Times, May 6, 2003.

stage may include a return of IAEA monitoring of nuclear material stocks (including weapons-
usable separated plutonium) and verification of actual weapons dismantlement. The question of
dismantling North Korea’s nuclear warheads has not yet been addressed directly, although the
September 2005 joint statement commits North Korea to abandon all nuclear weapons. Assistant
Secretary Christopher Hill has said that the issue of which states will participate in the
verification is under discussion, but may include the nuclear-weapon states amongst the six
parties: the United States, Russia, and China. Critics have raised concerns about the lack of clear
verification provisions for these steps and the omission of specific references to key issues such
as fissile materials, warheads, the reported uranium enrichment program, and the nuclear test site 34
in the latest agreements. In remarks to journalists, Assistant Secretary Hill has said that warhead
dismantlement will be addressed in the next stage—the “endgame” or the “weapons phase”—35
which he hoped would start at the beginning of 2008.

The U.S. Director of National Intelligence confirmed that North Korea conducted an underground 37
nuclear explosion on October 9, 2006, in the vicinity of P’unggye. However, the sub-kiloton
yield of the test suggests that the weapon design or manufacturing process likely needs 38
improvement. North Korea reportedly told China before the test that it expected a yield of 4 39
kilotons, but seismic data confirmed that the yield was less than 1 kt. Radioactive debris 40
indicates that the explosion was a nuclear test, and that a plutonium device was used. It is 41
widely believed that the warhead design was an implosion device. Uncertainties remain about
when the plutonium used for the test was produced and how much plutonium was in the device,

Ileana Ros-Lehtinen,Verification Holds the Key,The Washington Times, October 7, 2007; Sharon Squassoni,
“Partial Progress,The Guardian, October 9, 2007; Bruce Klingner, “North Korea: Worrisome Gaps in Six-Party
Talks’ Joint Statement,” Heritage Foundation WebMemo No. 1655, October 4, 2007.
35 On-the-Record Briefing by Assistant Secretary of State for East Asian and Pacific Affairs and Head of the U.S.
Delegation to the Six-Party Talks Christopher R. Hill On His Upcoming Trip and the Six-Party Talks, U.S. State
Department, August 29, 2007, at
36 See also CRS Report RL33709, North Korea's Nuclear Test: Motivations, Implications, and U.S. Options, by Emma
Chanlett-Avery and Sharon Squassoni.
37Analysis of air samples collected on October 11, 2006 detected radioactive debris which confirms that North Korea
conducted an underground nuclear explosion in the vicinity of P.unggye on October 9, 2006. The explosion yield was
less than a kiloton. ODNI News Release No. 19-06, at
38 By comparison, a simple plutonium implosion device normally would produce a larger blast, perhaps 5 to 20
kilotons. The first nuclear tests conducted by other states range from 9 kt (Pakistan) to 60kt (France), but tests by the
United States, China, Britain, and Russia were in the 20kt-range.
39 Mark Mazzetti, “Preliminary Samples Hint at North Korean Nuclear Test,” New York Times, October 14, 2006, at
40 Thom Shanker and David Sanger, “North Korean fuel identified as plutonium,New York Times, October 17, 2006,
at A debate on this issue can be found in the November
2006 issue of Arms Control Today, at
41 Implosion devices, which use sophisticated lenses of high explosives to compress fissile material, are generally
thought to require testing, although the CIA suggested in 2003 that North Korea could validate a simple fission nuclear
weapons design using extensive high explosives testing. CIA response to questions for the record, August 18, 2003,
submitted by the Senate Select Committee on Intelligence, at

although a prominent U.S. nuclear scientist has estimated that North Korea likely used 42
approximately 6 kg of plutonium for the test.
The test’s low yield may not have been a failure. Another possibility is that the test’s low yield
was intentional—a sophisticated device designed for a Nodong medium range missile.
Alternatively, a low yield could have been intended to avoid radioactive leakage from the test site 43
or to limit the amount of plutonium used.

Secretary of State Colin Powell in December 2002 stated, “We now believe [the North Koreans] 44
have a couple of nuclear weapons and have had them for years.” In February 2005, North Korea 45
officially announced that it had “manufactured nukes for self-defense.” Although North Korea
has tested one device, Vice Foreign Minister Kim Gye Gwan has previously said that North 46
Korea possesses multiple bombs and was building more.
A key factor in assessing how many weapons North Korea can produce is whether North Korea
needs to use more or less material than the IAEA standards of 8kg of Pu and 25kg for HEU per 47
weapon. The amount of fissile material used in each weapon is determined by the design
sophistication. There is no reliable public information on North Korean nuclear weapons design.
In all, estimates of North Korea’s separated plutonium range between 30 and 50 kg, with an 48
approximate 5 to 6 kg of this figure having been used for the October 2006 test. This amounts to
enough plutonium for approximately five to eight nuclear weapons, assuming 6 kg per weapon.
After the test, North Korean could possess four to seven nuclear weapons. An unclassified
intelligence report to Congress says that “prior to the test North Korea could have produced up to

50 kg of plutonium, enough for at least a half dozen nuclear weapons” and points out that 49

additional plutonium is in the fuel of the Yongbyon reactor. Under Secretary Christopher Hill 50
has also cited the 50 kg estimate.

42 Siegfried Hecker, “Report on North Korean Nuclear Program,” Center for International Security and Cooperation,
Stanford University, November 15, 2006.
43 Siegfried Hecker, “Report on North Korean Nuclear Program,” Center for International Security and Cooperation,
Stanford University, November 15, 2006.
44 Transcript of December 29, 2002, Meet the Press.
45 James Brooke,North Korea says it has atom arms It will boycott talks on ending program; arsenal called self-
defense against Bush,” The New York Times, February 11, 2005.
46We have enough nuclear bombs to defend against a U.S. attack. As for specifically how many we have, that is a
secret. “North Korea Admits Building More Nuclear Bombs,ABC News, June 8, 2005, at
47 IAEA Safeguards Glossary:
48 Siegfried Hecker estimates 40-50 kg of separated plutonium and 6 kg for the test; David Albright and Paul Brannan’s
study says 33-55 kg of separated plutonium and roughly 5 kg for the test. U.S. Assistant Secretary of State Christopher
Hill cites 50 kg in his comments. Hecker, ibid. David Albright and Paul Brannan, “The North Korean Plutonium Stock
February 2007,” Institute for Science and International Security, February 20, 2007. Christopher Hill,Interview on
PBS NewsHour,” October 3, 2007, at
49 Unclassified Report to Congress on Nuclear and Missile Programs of North Korea, Office of the Director of National
Intelligence, August 8, 2007.
50 Joint Hearing on the North Korea Six-Party Process, House Committee on Foreign Affairs, Subcommittee on Asia,

Additional questions arise in determining how much plutonium North Korea has produced since
2002 when the IAEA monitors were kicked out of the country and the seals were broken at
Yongbyon. A South Korean Defense Ministry white paper from December 2006 estimated that
North Korea had made 30 kg of weapons-grade plutonium in the previous three years, potentially
enough for five nuclear bombs. It also concurred with U.S. estimates that North Korea’s total 51
stockpile of weapons-grade plutonium was 50 kg.

Estimates of plutonium production depend on a variety of technical factors, including the average
power level of the reactor, days of operation, how much of the fuel is reprocessed and how
quickly, and how much plutonium is lost in production processes. North Korean officials claimed
to have separated plutonium in hot cells as early as 1975 and tested the reprocessing plant in
1990. North Korea’s 5MWe nuclear reactor at Yongbyon operated from 1986 to 1994. It is
estimated that North Korea produced and separated no more than 10 kg of plutonium prior to 52
1994. Its plutonium production program was then frozen between 1994 and 2003 under the
Agreed Framework. When this agreement was abandoned, North Korea restarted plutonium
production at Yongbyon.
On February 6, 2003, North Korean officials announced that the 5MWe reactor was operating,
and commercial satellite photography confirmed activity in March. In January 2004, North
Korean officials told an unofficial U.S. delegation that the reactor was operating smoothly at
100% of its rated power. The U.S. visitors noted that the display in the reactor control room and
steam plumes from the cooling towers confirmed operation, but that there was no way of knowing 53
how it had operated over the last year.
The same delegation reported that the reprocessing “facility appeared in good repair,” in contrast
to a 1992 IAEA assessment of the reprocessing plant as “extremely primitive.” According to
North Korean officials in January 2004, the reprocessing plant’s annual throughput is 110 tons of
spent fuel, about twice the fuel load of the 5MWe reactor. Officials claimed to have reprocessed 54
all 8,000 fuel rods from the 5MWe reactor between January and June 2003. Reprocessing the

8,000 fuel rods would yield between 25 and 30kg of plutonium, perhaps for four to six weapons,

but the exact amount of plutonium that might have been reprocessed is unknown. In 2004, North
Korean officials stated that the reprocessing campaign was conducted continuously (in four six-
hour shifts).
In April 2005, the 5MWe reactor was shut down, this time to harvest fuel rods for weapons.55 The 56
reactor resumed operations in June 2005. One estimate is that the reactor held between 10 and

the Pacific and the Global Environment and Subcommittee on Terrorism, Nonproliferation and Trade, October 25,
“North Korea ‘serious threat’ to South,BBC News,
52 David Albright and Paul Brannan, “The North Korean Plutonium Stock February 2007.”
53 Siegfried Hecker, January 21, 2004, testimony before Senate Foreign Relations Committee.
54 “North Korea Says It Has Made Fuel For Atom Bombs,New York Times, July 15, 2003.
55North Koreans Claim to Extract Fuel for Nuclear Weapons,” New York Times, May 12, 2005.

15 kg of Pu in April 2005, and that North Korea could have reprocessed all the fuel rods by mid-

2006. From August 2005 to 2006, the reactor could have produced another 6 kg of Pu. In total,

North Korea could have reprocessed enough separated plutonium for another three weapons (in 57
addition to the estimated 4-6 bomb-worth from reprocessing the 8,000 fuel rods). The 5MWe
reactor was again shut down in July 2007, when the IAEA installed containment and surveillance 58
measures and radiation monitoring devices.
The reactors at Yongbyon (50MWe) and Taechon (200MWe) are several years from completion. 59
No construction has occurred at the 50MWe reactor or at the 200MWe reactor since 2002. U.S.
visitors in January 2004 saw heavy corrosion and cracks in concrete building structures at 60
Yongbyon, reporting that the reactor building “looks in a terrible state of repair.” The CIA
estimated that the two reactors could generate about 275kg of plutonium per year if they were 61
operating. Dr. Hecker estimated that if the 50MWe reactor was functioning, it would mean a 62
tenfold increase in North Korea’s plutonium production. North Korea agreed to halt work on
reactors as part of the Six Party Talks. As of July 2007, the IAEA is monitoring to ensure that no
further construction takes place at these sites.
Significant future growth in North Korea’s arsenal would be possible only if the two larger
reactors were completed and operating, and would depend on progress in the reported uranium
enrichment program. With construction of the 50MWe and 200MWe reactors shuttered and the
Yongbyon facilities awaiting disablement and eventual dismantlement, North Korean plutonium
production for the moment has stopped. The reprocessing facility is also now shut down and
under IAEA monitoring. However, even with the reprocessing facility shut down, North Korea
could build additional warheads with existing separated plutonium because North Korea’s
plutonium stocks are not yet under IAEA safeguards.

While North Korea’s weapons program has been plutonium-based from the start, in the last
decade, intelligence has emerged pointing to a second route to a bomb using highly enriched
uranium. There is some certainty that North Korea has parts and plans for such a program, and
less certainty over how far this program has developed. The issue has been central to negotiations
since October 2002, when the Bush Administration accused North Korea of having a clandestine

56 David Albright and Paul Brannan, “The North Korean Plutonium Stock February 2007,” Institute for Science and
International Security, February 20, 2007.
57 Technical difficulties associated with the fuel fabrication facility may have slowed how often the fuel was unloaded
from the reactor, limiting production to at most one bomb per year. Siegfried Hecker, “Report on North Korean
Nuclear Program, Center for International Security and Cooperation, Stanford University, November 15, 2006.
58 IAEA Team Confirms Shut Down of DPRK Nuclear Facilities,
59 Report by the Director General to the IAEA Board of Governors,Applications of Safeguards in the Democratic
Peoples Republic of Korea (DPRK),” GOV/2007/45-GC(51)/19, August 17, 2007.
60 Hecker January 21, 2004, testimony before SRFC.
61 CIA unclassified point paper distributed to congressional staff on November 19, 2002.
62 Siegfried Hecker, “Report on North Korean Nuclear Program,” Center for International Security and Cooperation,
Stanford University, November 15, 2006.

uranium enrichment program. U.S. lead negotiator James Kelly told North Korean First Deputy
Foreign Minister Kang Sok-chu that the United States had evidence of a uranium enrichment
program for nuclear weapons in violation of the Agreed Framework and other agreements. James
Kelly said that Kang acknowledged the existence of such a program at that meeting. However,
Kang later denied this, and Foreign Minister Paek Nam Sun said that Kang had told Kelly that
North Korea is “entitled” to have such a program or “an even more powerful one” to deter a pre-63
emptive U.S. attack.
A 2002 unclassified CIA working paper on North Korea’s nuclear weapons and uranium
enrichment estimated that North Korea “is constructing a plant that could produce enough
weapons-grade uranium for two or more nuclear weapons per year when fully operational—
which could be as soon as mid-decade.” Such a plant would need to produce more than 50kg of 64
HEU per year, requiring cascades of thousands of centrifuges. The paper noted that in 2001,
North Korea “began seeking centrifuge-related materials in large quantities.” Pakistani President
Musharraf revealed in his September 2006 memoir, In the Line of Fire, that Abdul Qadeer
Khan—chief scientist in Pakistan’s nuclear weapons program who proliferated nuclear weapons
technology for profit—”transferred nearly two dozen P-1 and P-2 centrifuges to North Korea. He
also provided North Korea with a flow meter, some special oils for centrifuges, and coaching on 65
centrifuge technology, including visits to top-secret centrifuge plants.” However, the United
States has not been able to get direct confirmation from Khan. According to press reports, North
Korea said it had imported 150 tons of high-strength aluminum tubes from Russia that could be 66
used in a uranium enrichment program.
Questions have been raised about whether the 2002 estimates were accurate.67 In a hearing before
the Senate Armed Services Committee on February 27, 2007, Joseph DeTrani, the mission
manager for North Korea from the Office of the Director of National Intelligence and former
chief negotiator for the Six Party Talks, was asked by Senator Jack Reed whether he had “any
further indication of whether that program has progressed in the last six years, one; or two, the
evidence—the credibility of the evidence that we had initially, suggesting they had a program
rather than aspirations?” DeTrani responded that “the assessment was with high confidence that,
indeed, they were making acquisitions necessary for, if you will, a production-scale program. And
we still have confidence that the program is in existence—at the mid-confidence level.” In a
clarification of his response, DeTrani issued a DNI press release that said there was a high level
of confidence in 2002 that North Korea had a uranium enrichment program, and “at least
moderate confidence that North Korea’s past efforts to acquire a uranium enrichment capability

Selig Harrison, “Did North Korea Cheat?” Foreign Affairs, vol. 84, no. 1, January/February 2005.
64 North Korea would first have to convert uranium “yellowcake into uranium hexaflouride to feed into the
centrifuges. The centrifuges would “enrich the uranium, or increase the portion of U-235. Weapons-grade enriched
uranium according to the IAEA needs to have an enrichment level of at least 20%. See CRS Report RL34234,
Managing the Nuclear Fuel Cycle: Policy Implications of Expanding Global Access to Nuclear Power, by Mary Beth
Nikitin, Anthony Andrews, and Mark Holt.
65 Pervez Musharraf, In the Line of Fire: A Memoir, (New York: Free Press, September 2006), p. 296.
66NK Admits to Buying Aluminum Tubes, KBS World News, September 27, 2007, and Takashi Sakamoto,”DPRK
Admits To Importing Aluminium Tubes From Russia for Uranium Enrichment, Yomiuri Shimbun, in Japanese,
Translated by BBC Monitoring Asia Pacific, October 26, 2007.
67 Paul Kerr,News Analysis: Doubts Rise on North Koreas Uranium-Enrichment Program, Arms Control Today,
April 2007, at

continue today.”68 Assistant Secretary Christopher Hill said in February 2007 that the United
States is not sure if North Korea has mastered “some considerable production techniques,” 69
although they have acquired some technology for an enrichment program.
A DNI unclassified report of August 2007 stated,
We continue to assess with high confidence that North Korea has pursued efforts to acquire a
uranium enrichment capability, which we assess is intended for nuclear weapons. All
Intelligence Community agencies judge with at least moderate confidence that this past effort
continues. The degree of progress towards producing enriched uranium remains unknown, 70
In testimony to Congress on February 2008, Director of National Intelligence Michael McConnell
confirmed this assessment. The confidence level of these assessments may have changed because
of a decrease in international procurement by North Korea. Uranium enrichment-related imports
would be more easily detected by intelligence agencies than activities inside North Korea itself.
Uranium enrichment facilities can be hidden from aerial surveillance more easily than plutonium
facilities, making it more difficult for intelligence agencies to even detect—thus, “degree of
progress” in turning the equipment into a working enrichment program is “unknown.”
Furthermore, there are significant differences between assembling a small-scale centrifuge
enrichment program and operating a large-scale production plant, and reportedly little evidence of 71
procurement for a large-scale plant has emerged.
As part of the February 2007 agreement in the Six-Party talks, North Korea agreed to provide a
“complete declaration of all nuclear programs and disablement of all existing nuclear facilities,”
and has pledged to do so by the end of 2007. U.S. officials have said that this will include any
uranium enrichment activities. Assistant Secretary Christopher Hill in testimony to Congress in
October 2007 said that he expects transparency on the uranium enrichment program by the end of 72


North Korea reportedly continues to deny the existence of a highly enriched uranium program for
weapons. North Korea gave the United States a sample of the aluminum tubing in an effort to
prove that it never intended to produce highly enriched uranium for weapons, and that the

68There has been considerable misinterpretation of the Intelligence Communitys view of North Korean efforts to
pursue a uranium enrichment capability. The intelligence in 2002 was high quality information that made possible a
high confidence judgment about North Koreas efforts to acquire a uranium enrichment capability. The Intelligence
Community had then, and continues to have, high confidence in its assessment that North Korea has pursued that
capability. We have continued to assess efforts by North Korea since 2002. All Intelligence Community agencies have
at least moderate confidence that North Korea’s past efforts to acquire a uranium enrichment capability continue
today.” ODNI News Release 04-07, March 4, 2007, at
69 “Update on the Six Party Talks, Brookings Institution, February 22, 2007, at
70 Unclassified Report to Congress on Nuclear and Missile Programs of North Korea, Office of the Director of National
Intelligence, August 8, 2007.
71 See David Albright, “North Koreas Alleged Large-Scale Enrichment Plant: Yet Another Questionable Extrapolation
Based on Aluminum Tubes,” The Institute for Science and Security, February 23, 2007, at
72 Statement of Christopher R. Hill Assistant Secretary, Bureau of East Asian and Pacific Affairs, Department of State
before the House Committee on Foreign Affairs, Subcommittee on Asia, the Pacific and the Global Environment and
Subcommittee on Terrorism, Nonproliferation and Trade, Joint Hearing on the North Korea Six-Party Process, October
25, 2007.

imported materials were for conventional weapons or dual-use projects. However, when U.S.
scientists analyzed the aluminum tubing provided as sample “evidence,” they found traces of
enriched uranium on the tubing. Analysts argue that in addition to the possibility that this is proof
of a North Korean uranium enrichment program, it is also possible that the uranium traces could 73
have been on the tubing when North Korea received it. This issue remains unresolved.

Although former Defense Intelligence Agency (DIA) Director Lowell Jacoby told the Senate
Armed Services Committee in April 2005 that North Korea had the capability to arm a missile
with a nuclear device, Pentagon officials later backtracked from that assessment. A DNI report to
Congress says that “North Korea has short and medium range missiles that could be fitted with 74
nuclear weapons, but we do not know whether it has in fact done so.” North Korea has several
hundred short-range Scud-class and medium range No Dong-class ballistic missiles, and is
developing an intermediate range ballistic missile. The Taepo-Dong-2 that was tested
unsuccessfully in July 2006 would be able to reach the continental United States if it becomes
operational. DNI assessed in 2008 that the Taepo-Dong-2 has the potential capability to deliver a
nuclear-weapon-sized payload to the United States, but that absent successful testing the 75
likelihood of this is low.
It is possible that Pakistani scientist A.Q. Khan may have provided North Korea the same
Chinese-origin nuclear weapon design he provided to Libya and Iran. Even though that design
was for an HEU-based device, it would still help North Korea develop a reliable warhead for
ballistic missiles—small, light, and robust enough to tolerate the extreme conditions encountered
through a ballistic trajectory. Learning more about what is needed for miniaturization of warheads 76
for ballistic missiles could have been the goal of North Korea’s testing a smaller nuclear device.

U.S. officials in their threat assessments have described the North Korean nuclear capabilities as
being more for deterrence and coercive diplomacy than for warfighting, and assess that
Pyongyang most likely would “not attempt to use nuclear weapons against U.S. forces or territory
unless it perceived the regime to be on the verge of military defeat and risked an irretrievable loss 77
of control.” Statements by North Korean officials emphasize that moves to expand their nuclear

73 Glenn Kessler, “Uranium Traces Found on N. Korean Aluminum Tubes, Washington Post, December 21, 2007, at
74 Unclassified Report to Congress on Nuclear and Missile Programs of North Korea, Office of the Director of National
Intelligence, August 8, 2007. Also see CRS Report RS21473, North Korean Ballistic Missile Threat to the United
States, by Steven A. Hildreth.
75 Annual Threat Assessment of the Director of National Intelligence for the Senate Select Committee on Intelligence,
February 5, 2008, at
76 “Technical Perspective on North Korea’s Nuclear Test: A Conversation between Dr. Siegfried Hecker and Dr. Gi-
Wook Shin,” Stanford University website, October 10, 2006, at
technical_perspective_ on _north _ko reas_nuclear_test_a_ conversation_between_dr_siegfried_hecker _and_dr_giwook_s
77 Annual Threat Assessment of the Director of National Intelligence for the Senate Select Committee on Intelligence,
February 5, 2008, at

arsenal are in response to perceived threats by the United States against the North Korean 78
regime. Nuclear weapons also give North Korea leverage in diplomatic negotiations, and
threatening rhetoric often coincides with times of crisis in negotiations. In January 2008, a North
Korean media report stated that the country “will further strengthen our war deterrent capabilities
in response to U.S. attempts to initiate nuclear war.” This statement came as North Korea was 79
expressing its displeasure that it had not yet been removed from the U.S. terrorism list.

Congress will have a clear role in considering U.S. funding for the disablement and
decommissioning of North Korea’s nuclear facilities, as well as other inducements for
cooperation as agreed in the Six Party talks. For example, the President has submitted a request to
Congress for $106 million “to provide Heavy Fuel Oil or an equivalent value of other assistance
to North Korea on an ‘action-for-action’ basis in support of the Six Party Talks in return for 80
actions taken by North Korea on denuclearization” as part of the 2008 War Funding Request.
This amount was approved in the Omnibus Appropriations bill for FY2008 passed in December


Congress could also play a role in establishing legal authority for assistance to nuclear
disablement and dismantlement in North Korea. The Departments of State and Energy are now
working to dismantle the nuclear facilities at the Yongbyon complex in North Korea. This effort is
being funded through the State Department’s Nonproliferation and Disarmament Fund (NDF).
NDF funds may be used “notwithstanding any other provision of law” and therefore may be used
in North Korea. Since North Korea conducted a nuclear test in October 2006, Section 102 (b) (the
“Glenn Amendment” U.S.C. 2799aa-1) of the Arms Export Control Act prohibits assistance to a
non-nuclear weapon state under the NPT that has detonated a nuclear explosive device. A
possible solution under discussion would be to carve out an exception to the Glenn amendment
specifically for North Korean nuclear disablement and dismantlement, which would require 81
congressional action.
Beyond the Glenn amendment restrictions, Department of Defense funds must be specifically
appropriated for use in North Korea. Section 8045 of the FY2008 Defense Appropriations Act
says that “None of the funds appropriated or otherwise made available in this Act may be
obligated or expended for assistance to the Democratic People’s Republic of Korea unless
specifically appropriated for that purpose.” However, this year authorization was given for CTR
funds to be used globally (see Section 1305). The FY2008 Defense Authorization Act specifically
encourages “activities relating to the denuclearization of the Democratic People’s Republic of
Korea” as a potential new initiative for CTR work. Currently, the Department of Defense is not
working on disablement efforts, but there may be a future role for DOD is the Six Party process
progresses to dismantlement work.

78 See, for example, North Koreas statement of February 10, 2005, at
79North Korea says nuclear declaration submitted,” Reuters, January 4, 2008.
2008 War Funding Request, October 22, 2007, at
81 Peter Crail, “U.S.-NK Clash on Nuclear Deadline,Arms Control Today, January/February 2008.

Congress expressed concern that the Department of Energy have enough funds available to
support the disablement of North Korea’s nuclear weapons arsenal and production capability. In
the FY2008 Omnibus Appropriations Act, the Committees on Appropriations provided DOE’s
NNSA with funding discretion to provide up to $10 million towards its activities in North Korea.
It also directs the Department to submit a supplemental budget request if additional resources are 82
required during FY2008.
In addition, Congress may influence the course of the negotiations with North Korea through
legislation that limits or places requirements on U.S. diplomatic actions. For example, H.R. 3650
has been introduced and referred to the House Foreign Affairs Committee, calling for certification
by the President that North Korea has met a range of nonproliferation and political benchmarks
before lifting any U.S. sanctions imposed because it has been deemed a supporter of international 83
terrorism by the Secretary of State. Congress could also establish reporting requirements on
progress, or condition appropriations or disbursement to North Korea upon verification measures.
Congress could also be involved in other aspects of potential changes in U.S. relations with
Pyongyang, such as removal from the state sponsors of terrorism list, monitoring of the North
Korean human rights issues, funding for further denuclearization steps including verification
provisions, and establishment of normalized ties once nuclear dismantlement has been achieved.
Mary Beth Nikitin
Analyst in Nonproliferation, 7-7745

82 See p. 50 of
83 H.R. 3650, September 25, 2007.