1. State Participation in Nonproliferation Regime Networks
Sarah Laderman
2017 Winter PONI Conference

2. Research Overview & Motivation
Utilize network science to assess efficacy of Nuclear Nonproliferation Treaty (NPT) and Nuclear Weapon Free Zones (NWFZs)
As nonproliferation networks become larger and more connected, global nuclear proliferation levels should decrease
Motivated by Ban Treaty negotiations
Should research past multilateral nuclear nonproliferation treaties to inform future efforts

3. Source: UN Office for Disarmament Affairs, https://www. un

4. Network Design
Affiliation Network: nodes are states and treaties

5. Network Design Affiliation Network: nodes are states and treaties NPT
NWFZ
State 1 1
State 2
State 3
State 4

6. Network Design Affiliation Network: nodes are states and treaties NWFZ
NPT
State 1
State 2
State 3
State 4
NPT
NWFZ
State 1 1
State 2
State 3
State 4

7. Network Calculations
Eigenvector Centrality (EVC): measures centrality of node and its connected nodes
State centrality depends on centrality of treaties of which it is a member
Treaty centrality depends on centrality of member states
Two different tests using EVC
Effects on individual state proliferation
Effects on global proliferation

8. Test 1: State Proliferation
For each year, correlated state EVC with state proliferation level
Hypothesis: as state EVC increases, state proliferation should decrease
State proliferation level coding:
0  No Activity
1  Explore
2  Pursue
3  Acquire
Sources: Sonali Singh and Christopher R. Way, “The Correlates of Nuclear Proliferation: A Quantitative Test,” Journal of Conflict Resolution 48, no. 6 (December 2004) Christopher R. Way, “Nuclear Proliferation Dates,” June 12, 2012,

9. Test 1: Data Supports Hypothesis

10. Test 2: Global Proliferation
Over all years, correlated treaty EVC with global proliferation levels
Hypothesis: as treaty EVC increases, global proliferation should decrease
Global proliferation level is the sum of all individual state proliferation levels in the network

11. Test 2: Data Partially Supports Hypothesis
**p < 0.01; n = 34
NPT
NWFZ
EVC / Global Proliferation Correlation Coefficient
0.462**
-0.666**
NPT results do not support hypothesis
Positive correlation, statistically significant
NWFZ results support hypothesis
Negative correlation, statistically significant

12. Conclusions
NPT and NWFZ membership seems to be a self-enforcing mechanism encouraging nonproliferation tendencies in the individual state
As NWFZs become more integrated into the global nonproliferation treaty regime, NWFZs gain in efficacy
No evidence for NPT effect on global nonproliferation norms

13. Policy Implications
Demonstrates the utility of network science for nuclear nonproliferation policy analysis
NPT negotiations likely more effective on case-by-case basis
Negative implications for Ban Treaty
Spreading NWFZs to more regions may aid in global nonproliferation
Positive implication for NWFZs, e.g., Middle Eastern NWFZ

14. Acknowledgements and Disclaimer
Contact Information
Sarah Laderman
Acknowledgements and Disclaimer
I would like to thank my Complexity Group co-researchers from (1) UC Berkeley: Bethany Goldblum, Elie Katzenson, Nathanial Mahowald, Yara Mubarak, Suchismita Padhy, Lakshmi Ramesh, Andrew Reddie, Christopher Stewart, Austin Wright; (2) National Securities Technologies, LLC: Hart Kornell; and (3) Sandia National Laboratories: Zoe Gastelum. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA Disclaimer: This presentation was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

15. Backup Slides

16. Test 1: 1974 Full Data 1974 networks support hypothesis
Signature Network Correlation Coefficient = (p = 0.041)
Ratification Network Correlation Coefficient = (p = 0.003)

17. Test 1: Full Results

18. Test 2: Full Data
Treaty EVCs versus Global Proliferation Levels

19. Correlation Coefficient
Test 2: Full Results
**p < 0.01; n = 34
NPT EVC /
Global Proliferation
Correlation Coefficient
NWFZ EVC /
Signature Network
0.462**
-0.666**
Ratification Network
0.486**
-0.492**
Data partially supports hypothesis
NPT
Positive correlations, statistical significance
Ratification has a less positive correlation than signature
NWFZ
Negative correlations, statistical significance
Signature has a more negative correlation than ratification