A technically-informed roadmap for
North Korea’s denuclearization
Siegfried S. Hecker, Robert L. Carlin
and Elliot A. Serbin
Center for International Security and Cooperation
Stanford University
May 28, 2018

 North Korea nuclear program
Governs size of
arsenal

Governs sophistication
of arsenal

Bomb-grade
Pu or HEU

Weaponization

Delivery system

• Physics, computers
• High explosives
• Detonators
• Initiators
• Machining
• Assembly
• Explosives tests
• Arming, fuzing, firing
• Nuclear testing

• Plane
• Boat
• Van
• Missile

• Most difficult part
• Reactors (Pu) or
enrichment (HEU)
Hydrogen bombs
-  Tritium
-  Deuterium
-  Li-6D

Governs threat
arsenal poses

The next chart shows the evolution of “nuclearization” over the past 26 years and its
interrelationship to political and diplomatic developments as presented in the history study.
https://cisac.fsi.stanford.edu/content/cisac-north-korea

 North Korea Nuclear Program – h:ps://cisac.fsi.stanford.edu/content/cisac-north-korea 
3 shades of green (dark best), 3 shades of red (dark worst) – (Stanford University CISAC
Year 

US 
Diplomacy 

DPRK 
Diplomacy 

Yongbyon 
Presence 

Plutonium 

U enrich. 

Tri<um/Li-6 
(H-bomb fuel) 

Missiles 

Imports 

Exports 

1992 

G1 

G1 

G1 

G2 

G1 

G1 

R1 

R1 

R1 

R1 

R1 

1993 

G2 

G2 

G1 

G2 

G1 

G1 

R1 

R1 

R1 

R1 

R1 

1994 

G3 

G3 

G1 

G2 

G1 

G1 

R1 

R1 

R1 

R1 

R1 

1995 

G3 

G3 

G3 

G3 

G1 

G1 

R1 

G3 

R1 

R1 

R1 

1996 

G3 

G3 

G3 

G3 

G1 

G1 

R1 

G3 

R1 

R1 

R1 

1997 

G2 

G2 

G3 

G3 

R1 

G1 

R1 

G3 

R1 

R2 

R1 

1998 

G2 

G2 

G3 

G3 

R1 

G1 

R1 

G3 

R1 

R2 

R1 

1999 

G3 

G3 

G3 

G3 

R1 

G1 

R1 

G3 

G1 

R2 

R3 

2000 

G3 

G3 

G3 

G3 

R1 

G1 

R1 

G3 

G1 

R2 

R3 

2001 

R2 

G2 

G3 

G3 

R1 

G1 

R1 

G3 

G1 

R2 

R3 

2002 

R3 

G2 

G3 

G3 

R1 

G1 

R1 

G3 

G1 

R2 

R3 

2003 

R2 

R2 

R3 

R3 

R1 

R1 

R2 

R2 

G1 

R2 

R3 

2004 

R2 

R1 

R3 

R3 

R1 

R1 

R2 

R2 

G1 

R2 

R3 

2005 

R1 

R1 

R3 

R3 

R1 

R1 

R2 

R2 

R1 

R2 

R3 

2006 

R1 

R2 

R3 

R3 

R1 

R1 

R2 

R2 

R1 

R2 

R3 

2007 

G2 

G1 

G3 

G1 

R1 

R1 

R1 

R1 

R1 

R1 

R3 

2008 

G2 

G1 

G3 

G1 

R1 

R1 

R1 

R1 

R1 

R1 

R2 

2009 

R1 

R1 

R2 

R1 

R2 

R2 

R2 

R2 

R1 

R2 

R2 

2010 

G1 

R1 

R3 

R1 

R2 

R2 

R2 

R2 

R1 

R2 

R2 

2011 

G1 

G1 

R3 

R1 

R2 

R2 

R2 

R2 

R1 

R2 

R2 

2012 

R1 

R1 

R3 

R1 

R2 

R2 

R2 

R2 

R1 

R2 

R2 

2013 

R2 

R1 

R3 

R2 

R2 

R2 

R2 

R2 

R1 

R2 

R1 

2014 

R2 

R1 

R3 

R2 

R3 

R3 

R2 

R2 

R1 

R2 

R1 

2015 

R1 

G1 

R3 

R3 

R3 

R3 

R2 

R2 

R2 

R2 

R1 

2016 

R1 

R3 

R3 

R3 

R3 

R3 

R3 

R3 

R2 

R2 

R1 

2017 

R3 

R3 

R3 

R3 

R3 

R3 

R3 

R3 

R3 

R2 

R1 

Weaponize 

Design/build/test 

Nukes 
(Summary) 

 Risk based approach to North Korea denuclearization
Nuclear and missile assets/activities
Specific facilities or
activities
Nuclear weapons

Nuclear arsenal

Personnel

Scientists, engineers

Nuclear tests

Nuclear tests
Tunnels
Test infrastructure

Missile Tests

IRBM &ICBM
SLBM & Solid rocket motors
New engine tests
Short & med.-range missiles
Space Launch Vehicles

Plutonium

Inventory
5MWe reactor
ELWR
IRT-2000
Reprocessing Facility
Metal fuel fab facilities

Fusion (H-bomb) fuels

Tritium
Lithium-6

Uranium Enrichment

HEU inventory
YB centrifuge facility
Covert centrifuge facilities

No export

Nuclear & missile technology

 Current US view of denuclearization
Risk posed by nuclear assets/activities – red (very high)
Specific facilities or
activities
Nuclear weapons

Nuclear arsenal

Personnel

Scientists, engineers

Nuclear tests

Nuclear tests
Tunnels
Test infrastructure

Missile Tests

IRBM &ICBM
SLBM & Solid rocket motors
New engine tests
SR & MR Missiles
Space Launch Vehicles

Plutonium

Inventory
5MWe reactor
ELWR
IRT-2000
Reprocessing Facility
Metal fuel fab facilities

Fusion (H-bomb) fuels

Tritium
Lithium-6

Uranium Enrichment

HEU inventory
YB centrifuge facility
Covert centrifuge facilities

No export

Nuclear & missile technology

ELIMINATE

- This graphic depicts the current US
demand of CVID denuclearization
(complete [or permanent], verifiable,
irreversible, dismantlement).
- Insisting on immediate CVID along a
“Libya model” to eliminate everything up
front and virtually all at once is tantamount
to a North Korean surrender scenario. It is
unimaginable that Kim will agree to a Libya
model.
- The scale of the programs is also
dramatically different. Libya never got close
to nuclear weapons. North Korea has a
threatening nuclear arsenal and a huge
complex. The suggestion of shipping the
North’s nuclear weapons out of the country
is naïve and dangerous. The weapons must
be disassembled by the people who
assembled them.
- Although US should be prepared to accept
all concessions Kim is willing to make early
on, such as closing the nuclear test site, it
must be prepared for a phased approach.
- One option is to still insist on CVID, but
space it out over time as in the next chart,
but this also unlikely to be acceptable to
Pyongyang.

 Alternate US view of denuclearization
Risk posed by nuclear assets/activities – red (very high)
Specific facilities or
activities
Nuclear weapons

Nuclear arsenal

Personnel

Scientists, engineers

Nuclear tests

Nuclear tests
Tunnels
Test infrastructure

Missile Tests

IRBM &ICBM
SLBM & Solid rocket motors
New engine tests
SR & MR Missiles
Space Launch Vehicles

Plutonium

Inventory
5MWe reactor
ELWR
IRT-2000
Reprocessing Facility
Metal fuel fab facilities

Fusion (H-bomb) fuels

Tritium
Lithium-6

Uranium Enrichment

HEU inventory
YB centrifuge facility
Covert centrifuge facilities

No export

Nuclear & missile technology

Short term
< 1 year

Medium term
2 to 5 years

Longer term – 6 to 10 years
CVID

 A technically-informed, risk management roadmap to “denuclearization.”
- Our history study shows that North Korea’s nuclear development has been deliberate and determined,
and not primarily predicated on cycles of provocations, appeasement and reversals. Diplomacy has several
times slowed or even reversed the program, but never eliminated it. There has been and continues to be a
huge trust deficit between the two sides that will almost certainly compel Pyongyang to hedge its bets in
any agreed path forward – as it did multiple times over the past 26 years.
- Our experience in dealing with the North has also taught us that retaining a civilian nuclear program and a
peaceful space program are of great importance to the North – both for technical and symbolic reasons.
Over the past 17 years, the US has considered such civilian activities as covers for military ambitions and
has consistently denied these, fearing that such activities would support the North’s military programs.
However, this type of risk avoidance instead of risk management has led to several missed opportunities to
halt and/or reverse the military programs.
- Today, the risk calculus is quite different from previous years. Unlike in the past, military programs are
now so advanced that the civilian programs pose little incremental risk, and their longer-term risks can be
managed.
- In the next chart, we propose a phased risk management approach to denuclearization by identifying
those assets and activities that pose the greatest risk and must be eliminated (shown in red) and those that
can be managed (shown in yellow). The mosaic is meant to provide an overall sense of what’s manageable
and what must be eliminated. The phases constitute what might be possible during the first year, the “halt”
stage, in years 2 to 5, the “roll back” stage, and in years 6 to 10, the “eliminate” stage. The details are
shown in a subsequent chart. Political development will, of course, determine whether or not that time
frame can be shortened or lengthened.

 A more sensible risk management roadmap to denuclearization (Hecker/Carlin/Serbin)
Risk posed by nuclear assets/activities – red (very high, must be eliminated), yellow (moderate – can be managed)
Specific facilities or
activities
Nuclear weapons

Nuclear arsenal

Personnel

Scientists, engineers

Nuclear tests

Nuclear tests
Tunnels
Test infrastructure

Missile Tests

IRBM &ICBM
SLBM & Solid rocket motors
New engine tests
SR & MR Missiles
Space Launch Vehicles

Plutonium

Inventory
5MWe reactor
ELWR
IRT-2000
Reprocessing Facility
Metal fuel fab facilities

Fusion (H-bomb) fuels

Tritium
Lithium-6

Uranium Enrichment

HEU inventory
YB centrifuge facility
Covert centrifuge facilities

No export

Nuclear & missile technology

HALT - short term
< 1 year

ROLL BACK- medium term
2 to 5 years

ELIMINATE or SET LIMITS long term – 6 to 10 years

 A technically-informed, risk management roadmap to “denuclearization.”
- Our detailed study of the North’s nuclear program identifies the most important initial steps to take
toward denuclearization to be: no nuclear tests, no intermediate or long-range missile tests, no
more production of plutonium and highly enriched uranium, and no export of nuclear weapons,
materials or technologies.
- The next chart suggests specific steps that can be phased in over three time horizons. In the short
term, North Korea will surely hedge its bets by retaining parts of the program. But the risks in the
yellow areas are manageable and will help focusing on the most immediate and pressing risks
shown in red. The phased approach will also provide an effective way to build trust and
interdependence, which are required for a viable long-term solution – complete demilitarization of
North Korea’s nuclear program.
- If the North insists on retaining civilian nuclear programs and peaceful space access, the
incremental risk posed by these can be managed if adequate verification measures can be
developed. Although an electricity-producing light water reactor can potentially be diverted to
plutonium production and a medical isotope research reactor can do the same, the risks are
manageable. They are less than those posed by North Korea’s current plutonium production
reactor. Likewise for space launch vehicles. These under proper verification protocols will not
advance the North’s ICBM program nearly as much as the current missile buildup.
- An agreement to have North Korea retain a civilian nuclear program and peaceful space program
also solves the nuclear and missile personnel redirection issue. In addition to transitioning to civilian
activities, the technical staff can help to decommission and clean up the facilities dedicated to the
weapons program. One can envision a professional staff reorientation along the lines of the NunnLugar program with Russia.
- The future of the uranium centrifuge program will also need to be determined. Currently it is
believed to be dedicated primarily to producing weapon-grade HEU. However, under proper
verification procedures, it could be restricted to producing LEU for light water reactors and be
adequately verified.
- We also suggest that the best verification measures will result from cooperative civilian nuclear
programs and space programs. That is, pursuing these ventures cooperatively between North
Korea, South Korea and the US (perhaps later with others) will provide a presence of technical
personnel at the North’s facilities that will greatly improve attaining adequate verification.

 A more sensible risk management roadmap to denuclearization (Hecker/Carlin/Serbin)
Risk posed by nuclear assets/activities – red (very high, must be addressed), yellow (moderate – can be managed)
Specific facilities or
activities

HALT - short term
< 1 year

ROLL BACK- medium term
2 to 5 years

ELIMINATE or SET LIMITS long term – 6 to 10 years

Nuclear weapons

Nuclear arsenal

Cap

Declare & reduce

Eliminate & verify. Join NPT

Nuclear personnel

Scientists, engineers, techs

Assist in halting operations

Assist in roll back

Redirect to civilian programs

Nuclear tests

Nuclear tests

Moratorium/suspend 

Ban 

Ban (sign CTBT) 

Tunnels

Suspend acNvity 

Close 

Destroy 

Test infrastructure

Suspend acNvity 

Dismantle 

Dismantle & verify  

IRBM &ICBM

Moratorium/suspend 

Declare , disable & monitor 

Destroy missiles, no developm.  

SLBM & Solid rocket motors

Moratorium/suspend 

Declare, disable  & monitor 

Destroy missiles, no developm.  

New engine tests

Suspend 

Halt & monitor 

Ban tests and development 

SR & MR Missiles

Short term suspension 

TBD – set allowable limits 

TBD – set allowable limits 

Space Launch Vehicles

Short term suspension 

TBD – establish protocol  

TBD – establish acceptable limits 

Inventory

Cap 

Cap, declare & monitor 

Eliminate 

5MWe reactor

Halt 

Dismantle 

Decommission 

ELWR

Halt or don’t start 

Inspect & future TBD 

TBD 

IRT-2000

Halt 

Dismantle 

Decommission, possibly replace 

Reprocessing facility

Don’t operate 

Dismantle front end (no new fuel) 

Dismantle & decommission 

Metal fuel fab facilities

Don’t operate 

Dismantle 

Decommission 

Tritium

Halt reactors ( as above) 

Dismantle reactors &  hot cells 

Eliminate 

Lithium-6

Halt producNon 

Dismantle producNon faciliNes 

Eliminate 

HEU inventory

Limit (halt support faciliNes) 

Cap, declare & monitor 

Eliminate 

YB centrifuge facility

Halt & inspect 

Inspect & future TBD 

TBD 

Covert centrifuge facilities

Limit (halt support faciliNes) 

Declare & inspect 

Eliminate 

Nuclear & missile technology

No export pledge 

No nuclear export. Join MTCR  

No nuclear export. Join MTCR  

Missile tests

Plutonium

Fusion (H-bomb) fuels

Uranium enrichment

No export

 A technically-informed, risk management roadmap to “denuclearization.”
 
- The approach suggested here is based on our belief that North Korea will not give up its weapons
and its weapons program until its security can be assured. Such assurance cannot be achieved
simply by an American promise or an agreement on paper, it will require a substantial period of coexistence and interdependence.
- The roadmap is designed to manage risks on the path to denuclearization. We believe it has a
chance of being supported by Pyongyang based on our experience in dealing with North Korea’s
diplomatic and technical communities. In practice, the path will necessarily be forged during long
and complicated negotiations. As shown in the charts, we have left many of the actions as to be
determined (TBD) during the negotiations.
- To make it attractive to the Trump administration, which has stated its desire to denuclearize
completely and quickly, it will be important for North Korea to front-end load as much of the
denuclearization process as possible. The May 24 demolition of the nuclear test site is one such
example. It moves the nuclear testing actions from the long term to the immediate term. We believe
several similar moves such as disabling the plutonium-production reactor could be achieved during
or before a summit (assuming one will occur).
- Uranium enrichment facilities will be problematic. North Korea has covert facilities that it is unlikely
to declare and eliminate initially. We believe that early access to the known Yongbyon centrifuge
facility and halting operations of the uranium chemical processing facilities that support all
enrichment activities are the most important initial steps. These will limit the amount of HEU that
could be produced covertly in the mean time and allow managing the risks until the fate of the
Yongbyon facility is decided and the covert facilities declared and dismantled.
- In addition to this general roadmap, it will be critical during negotiations to consider steps needed
to implement the agreements. In addition, the financial costs of each of the steps must be analyzed
and anticipated.
- Finally, this approach has become much more feasible in the past six months during which the
North and South have taken remarkable steps toward reconciliation. Together, they can establish a
path toward coexistence and interdependence, manage most of the financial burdens, and develop
verification protocols that were unimaginable for decades.
CTBT – Nuclear Comprehensive Test Ban Treaty
MTCR – Missile Technology Control Regime
NPT – Nuclear Nonproliferation Treaty