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North Korea’s history of deception to clandestinely develop its nuclear weapons program suggests that any type of monitoring and verification system would require onsite monitoring to supplement open-source intelligence and U.S. national technical means. On-the-ground monitoring would be indispensable, especially for a broad-scope agreement.

Yet such a task poses notable challenges. Unlike verification monitoring systems that were developed for arms control agreements between the United States and Russia, verification for a North Korea agreement would require a system capable of capturing information about multiple small facilities that were originally designed to be hidden. In addition to monitoring fissile material production, onsite monitoring would also be needed at missile production facilities in support of a production ban and at military sites where nuclear items are located and where internal access is not granted.

One approach that could provide flexibility for a range of monitoring applications would be the development of a nodal monitoring system (NMS). Increasing verification R&D investments now in the development of such a system would be an adaptable way to strengthen confidence in any potential future agreement with North Korea.

Assumptions About Monitoring in North Korea

Policymakers and negotiators involved in future monitoring talks with North Korea should insist on obtaining physical access to monitor facilities and installations. To this end, they need to be ready to deploy a flexible and effective system to address onsite monitoring in situations where full access may be limited. Some desired key attributes for such a system can be identified based on several educated assumptions.

First, North Korea may grant access to only one or a very limited number of its installations. As a result, a suitable monitoring system may need to start small but be capable of expanding in size over time and if greater access is later granted. In addition, North Korea’s nuclear weapons and missile complex has many different types of installations. These include R&D labs, test facilities, production and assembly facilities, and active military installations. In recognition of this complexity and breadth, a suitable approach would need to be adaptable and capable of being easily tailored to specific installations and the activities they host.

Pablo Garcia
Pablo Garcia retired from Sandia National Laboratories after a thirty-four-year career in critical infrastructure modeling and analysis, nuclear nonproliferation, robotics, and other technical areas. For his last three years, he was the chief of staff to the laboratories’ director.

Second, the geographic distance between these North Korean facilities should be considered as well. North Korean installations that may be subject to monitoring and verification activities are spread out around the country and are located in remote areas without good infrastructure for the services that a monitoring system and its deployed personnel would require. Accordingly, this monitoring system would need to provide some cost-effective, self-supporting infrastructure services with very little or no reliance on local infrastructure.

Third, accurate information (especially from open sources) about North Korea’s facilities is limited. Furthermore, trust between North Korea and other countries would be low early in the process of seeking verification, and relevant experts from other countries would likely have low confidence in information provided by North Korea for verification purposes. As a result, an effective monitoring system would need to be designed to circumvent deception and concealment.

Fourth, while North Korea would likely resist permitting a large group of onsite inspectors, there is a precedent for placing small numbers of inspectors at select locations. A verification system would need to minimize onsite staff and inspectors, and it must be planned in such a way as to extend remote monitoring where needed to cover wider areas. Inspectors should expect little to no cooperation and active attempts at concealment. The monitoring system should support probabilistic monitoring at key points and include strong anti-tampering capabilities.

Finally, onsite monitoring should be designed to last for a few years, and the system should be modular in design so that monitoring capabilities can evolve over time. Ensuring ways to sustain the monitoring system over the long term needs to be a design consideration from the start to minimize operational costs and to allow the system’s capabilities to be refreshed when needed. The system should also be readily capable of adapting to monitor additional installations, to downsize, or even to face removal when monitoring is no longer required.

A systematic approach that is well thought out based on these assumptions and attributes would provide flexibility for future negotiations in support of a range of readily implementable options. Chiefly, verification could require an onsite monitoring system that allows for scalability and adaptability while maintaining robustness to prevent deception and tampering. Further, such an approach should be designed to require minimal deployed personnel, self-support in the field, and long-term sustainment.

Design Requirements for a Nodal Monitoring System

The NMS concept was proposed by experts at the Center for Strategic Studies of the China Academy of Engineering Physics during a track 1.5 dialogue in 2018, held under the Chatham House rule. If designed and implemented correctly, the NMS could address the attributes listed above.

As shown in figure 1, a single node of an NMS is basically a continuous monitoring portal approach that involves one or multiple portals around the restricted area that is under observation. Each node would center on a restricted area to which inspectors are not granted access. The monitoring party would place a boundary around this area, a portal (or multiple portals) for inspecting incoming or outgoing items, sensors along the boundary to detect unapproved movement, and sensors at the portal(s) to screen for permitted or unpermitted items.

The NMS concept expands on this basic approach by nesting or layering multiple nodes, as shown in figure 2. Nodes could be added or removed over time if conditions such as trust, security, inventory, and permitted access were to change. This feature, while adding complexity, makes this concept scalable and adaptable—two of the key desirable characteristics stated above.

One potential model to monitor North Korea’s nuclear program is the system that was employed in the Soviet Union during the Cold War. Over thirty years ago, U.S. inspectors employed continuous portal monitoring under the Intermediate-Range Nuclear Forces Treaty at a solid rocket motor production facility in the city of Votkinsk. The design and operation of this monitoring system offers a wealth of experience applicable to the design and implementation of an NMS for North Korea, which could be considered an evolution of single-site or single-node continuous portal monitoring. After thirty years, many technical advances are now available that could be readily applied to reduce the requisite development costs and ensure the successful implementation of a more complex NMS, one that could be applied to multiple types of facilities and that could be used to screen for a variety of restricted items or materials.

Inevitably, successfully implementing an NMS in North Korea would pose certain challenges. The NMS concept is designed so that nodes can be dynamically added, removed, and even tailored for specific activities at a very granular level. But ensuring that the system has this flexibility means that adaptability must be prioritized from the outset of the design phase. Policymakers need to understand that limiting flexibility early on to curb costs would affect the future function and performance of the system as it evolves. Moreover, in addition to strong engineering and program management, the development team should include legal and treaty experts from the start to ensure that an NMS would be not only technically sound but also compliant with the terms of the treaty or agreement at play. Verification R&D investments made now would support the development of such a system, and making such investments could also provide negotiators and policymakers flexibility and leverage in future monitoring talks with North Korea.

Accordingly, a suitably crafted NMS would need to strike a balance between structure and flexibility through a modular design that would enable deployed inspectors to make future enhancements so they could take full advantage of the range of NMS capabilities. Doing tabletop exercises with mockups or with computer simulation tools to create digital twins as the NMS is developed would go a long way toward ensuring that the needs of inspectors are met as the situation on the ground changes.

Separately, the tailoring of each node would need to accommodate a wide range of geographies, node sizes, and item types. The target to be monitored can range from a large installation, a specific facility, or a building within an installation all the way down to a single room or vault. It could even be a specific item such as a warhead or mobile missile launcher. The nodes would need to make appropriate use of technologies to minimize personnel requirements, given likely limits on the number of permitted inspectors and other deployed personnel. Small nodes within the NMS architecture could be great candidates for unmanned or remote monitoring.

Finally, a robust architecture would be needed to connect the nodes within an installation and then to link those across installations or multiple regions. This architecture should ensure data and information integrity while enabling information sharing with partner entities that may be involved in supporting monitoring of an agreement with North Korea.

A Way to Ensure Rapid Implementation and Scalability

It is plausible that an agreement with North Korea could first permit onsite monitoring access to a specific installation or a very limited number of installations. Policymakers and negotiators would want to be ready to deploy an NMS without significant delays so as to immediately capitalize on North Korea’s commitments. By investing in the development of an NMS monitoring system now, potential monitoring parties could reduce the time required to implement the system once an agreement is reached. This would make it more difficult for North Korean facilities to employ concealment or deception between the time an agreement were reached and onsite monitoring were implemented.

One useful idea borrowed from physical security of critical facilities is to have the necessary key elements ready, integrated, and pretested for a fast initial implementation. Applied to the NMS, this could take the form of a node-in-a-box, designed for a rapid initial deployment. Once installed, a more comprehensive design and construction could follow, building on the initial deployed model. This arrangement would also provide a great opportunity to work with and build relationships with the monitored party at an early stage. Installations and facilities initially targeted for elimination as part of a treaty could be ideal candidates for initial NMS deployment sites.

A range of new technologies could facilitate a compact node-in-a-box and provide the foundations for a robust NMS. These include:

  • low-power electronics and encrypted communications for sensor nodes;
  • microgrids with renewable energy options to power the nodes at remote sites;
  • network-based secured video cameras, microwave detectors, and other sensors for effective implementation of monitored boundaries or perimeters;
  • small unmanned air vehicles for perimeter and boundary monitoring if such flights are allowed within approved corridors around monitored facilities;
  • artificial intelligence–based analysis of inspection images and sensor data to reduce the burden on deployed personnel;
  • blockchain solutions for authenticating data and ensuring the integrity of information;
  • a secured Internet of Things network to connect nodes that are unattended or infrequently attended to;
  • worldwide Wi-Fi coverage with systems like Starlink to provide communications capabilities at remote sites; and
  • modern data architectures to enable adaptability, scalability, sustainability, and appropriate information sharing with treaty partners or other third parties as required, tying the whole system together.


One of the key advantages of the NMS concept is its modularity. This feature would allow the NMS to be applied not only to monitoring scenarios involving North Korea but conceivably also to future onsite monitoring activities in other regions.

Furthermore, the same modular characteristic would be useful in facilitating multilateral engagement, joint development, and cost sharing with regional partners. Even the monitored country—in this case, North Korea—could participate in design reviews, red-teaming, acceptance testing, and even the design of some of the system’s elements within export-control limitations. Doing so would enable trust building and engagement with North Korea on a peer-to-peer level. North Korea’s active participation in NMS design, inspection, and testing or exercises would also increase Pyongyang’s confidence that the deployed monitoring system does not include any undeclared additional monitoring functionality. A joint or multilateral approach to development would instill confidence in the NMS design and implementation, while also ensuring that the model is transparent and readily accepted by all relevant parties.