The final verification measure


Picture this scene! A landscape seemingly untouched by human intervention.  No settlement, no construction as far as the eye can see. And then, suddenly, a convoy of off-road vehicles appears on this peaceful stretch of land. People pour out of them and start unpacking boxes of equipment, erecting tents and building a small camp town, practically out of nothing.

These people could be inspectors, well-trained and highly specialized experts, who set themselves up for an on-site inspection to verify whether or not a nuclear explosion has been conducted somewhere in the vicinity.

On-site inspections are the final verification measure to verify States’ compliance with the CTBT. They are launched to establish whether or not a nuclear explosion has been carried out.
An exercise in Chernobyl, Ukraine, in June 2007, examined radiation measurement procedures.

On-site inspections are conducted to verify States Parties’ compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). An on-site inspection is launched to establish whether or not a nuclear explosion has been carried out.  During such an inspection, facts might also be gathered to identify a possible violator of the Treaty. It thus constitutes the final verification measure under the CTBT.

Although not explicitly labeled as such, on-site inspections under the CTBT are challenge inspections, as they can only be carried out upon request by a State Party. The State Party subjected to such an inspection cannot refuse to allow it to take place.


Experts tested seismic aftershock monitoring equipment during an exercise in Sweden in August 2007.

It was an advantage to the negotiators of the CTBT that a number of disarmament treaties already existed that included on-site inspection mechanisms.  Still, the negotiations proved challenging. Negotiators had to strike a fine balance between the expected benefits and the political risks.

A key benefit of an on-site inspection regime is that it deters potential violators from conducting nuclear explosions in the first place.  It thus increases confidence in States’ compliance with the Treaty.  Provisions for on-site inspections strengthen the notion of a verifiable Treaty and thus help garner support for it.

The on-site inspection regime deters potential violators from conducting nuclear explosions.
An exercise on radiation measurements took place in the Chernobyl exclusion zone in Ukraine in June 2007.

On the risk side of the balance sheet is the false sense of security on-site inspections could create. An inspection may fail to prove an actual violation which may have ensuing political implications, and an inspection may not be carried out due to implied costs and complexity. During the CTBT negotiations, the risk-benefit discussion concentrated on how to ensure a State Party’s right to protect its national security versus conducting an effective and thorough on-site inspection.

On-site inspection in the Treaty
The Treaty stipulates that on-site inspections can only be invoked once the Treaty has entered into force.  The Treaty prescribes how an inspection is triggered; how it is prepared and conducted; what techniques and procedures can be applied; which information an inspection report should contain; and what possible steps could follow the report’s examination by the organization’s main executive organ, the Executive Council. The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is now working to build up the OSI regime, so that the OSI capability will be available following the Treaty’s entry into force.

On-site inspections can only be invoked once the Treaty has entered into force.

When looking at the steps preceding an on-site inspection, it becomes immediately clear that the Treaty emphasizes speed.  The various phases are measured in hours and days. The result of this swift preparation process is an inspection team that is supposed to arrive at the border of the State Party to be inspected only six days after the request for the inspection was lodged. The schedule for considerations and decisions by Executive Council and the Director-General of the Technical Secretariat is very tight indeed.

Preparing for seismic aftershock monitoring during an exercise in Sweden in August 2007.

The main reason for this swiftness is the narrow time window during which some of the conclusive evidence for a Treaty violation can be obtained. The occurrence of seismic aftershocks after an event, for instance, declines with every passing day.  Equally, specific radioactive elements, i.e. particulates and noble gases, dissipate quickly due to their relatively short half-lives. Hence, an on-site inspection needs to start as soon as possible after a suspicious event to make use of these technologies and gather the respective data.

Preparations for an on-site inspection have to be swift, as there is only a narrow time window during which some of the conclusive evidence for a Treaty violation can be obtained.
Environmental sampling is an aspect of radiation measurements during an on-site inspection.

Guidelines on the duration of an on-site inspection are explicitly clear.  The inspection team has to submit a first progress report within 25 days after approval of the inspection by the Executive Council.  Unless the majority of the Executive Council members decide to discontinue the inspection, it can last for up to 60 days.  In exceptional cases and when the team considers an extension necessary, this time frame can be extended by 70 days to a total maximum of 130 days duration.

The requirements to prove a possible violation of the CTBT during an on-site inspection are unique.  These requirements apply not only to the time but also to the identification of the inspection area. There is inherent uncertainty in estimating the location of certain triggering events. Therefore, the area to be inspected under the CTBT OSI regime has been set at a maximum of 1000 km². This is still a fairly large area. Monitoring data and their analysis need to contribute to reducing the level of uncertainty in the location estimates.

Treaty provisions for on-site inspections strike a balance between effectiveness and the protection of the inspected State Party’s national security interests.

The Treaty provisions for the conduct of an on-site inspection reflect again the intention to maintain the balance between an effective inspection and the protection of the inspected State Party’s national security interests.  The inspected State Party must provide full access to the inspection area and give all necessary assistance to the inspection team to carry out its activities.

A field laboratory for radiation measurements during an exercise in Chernobyl, Ukraine, in June 2007.

The inspection team, for its part, strives to conduct the inspection without causing undue disturbances for the inspected State Party. In addition and upon request, the team must share all information, data and samples with the inspected State.

The Treaty requires a report to be prepared soon after the conclusion of the inspection. This report summarizes all findings of the inspection based on which the Executive Council makes a final assessment as to whether the Treaty has been violated, i.e. whether indeed a nuclear explosion has taken place.

The political sensitivity of on-site inspections finds another expression in the Treaty when it deals with unjustified on-site inspection requests. In the case that an on-site inspection request turns out to be “frivolous or abusive”, the requesting State Party may be subjected to rather stringent measures, such as paying for the costs of any preparations already made; having its right suspended to request another on-site inspection for some time; or having its right suspended to serve on the Executive Council for some time.

The Treaty foresees stringent measures in the case of “frivolous or abusive” on-site inspection requests.
Preparations for an overflight during an exercise in Croatia in July 2006.

The Treaty provides clear guidance as to the financing of an on-site inspection. From the moment the inspection team arrives on the territory of the State Party, the latter shall assist the team in arranging for transportation, accommodation, communication, interpretation services, meals and medical care.  Once the inspection is concluded, the State Party is reimbursed for all its expenses related to the stay and the activities of the inspection team on its territory.  This regulation is independent of the outcome of the inspection.

To prepare for effective on-site inspections, the CTBTO tests procedures and techniques in field experiments and simulation exercises.
All data acquired during an on-site inspection have to be stored for later reporting.

An on-site inspection is a major operation requiring well-tuned and careful preparation and implementation.  In order for it to work effectively, the CTBTO is testing all procedures and techniques of an on-site inspection in field experiments and table-top simulation exercises.  Workshops and training courses complement these efforts.

Operational Manual

The Operational Manual provides guidelines and procedures for all aspects of an on-site inspection. Here, mobile gamma radiation measurements.

States Signatories are currently elaborating a draft OSI Operational Manual, which will provide detailed procedures for all operational, technical and administrative aspects of an on-site inspection. The Treaty and its Protocol are already rather detailed. The OSI Operational Manual takes this level of detail even further. The Manual is required by the CTBT and, once adopted by the Conference of State Parties, will provide guidance on the implementation of relevant Treaty provisions.

States Signatories are developing a draft OSI Operational Manual, which will provide guidelines and procedures for all operational, technical and administrative aspects of an on-site inspection.
All elements of the OSI Operational Manual need to be tested.

The preparation of the draft OSI Operational Manual is a priority task of the CTBTO Preparatory Commission. States Signatories meet regularly as a task group under the chairmanship of the technical working group of the Preparatory Commission, the so-called Working Group B (WGB), to coordinate all drafting activities.

A draft outline of the OSI Operational Manual was developed in 1997 and subsequently the actual drafting process began. It resulted in the presentation of the Initial Draft Rolling Text. In May 2001, this first draft was adopted as a common basis for elaboration by States Signatories. In the four years that followed, States Signatories examined this text closely and provided comments, amendments and alternative proposals. In May 2005, the Annotated Draft Rolling Text was issued, taking into account all written input given by States Signatories during the first reading.

Since then, the Annotated Draft Rolling Text has been used as the basis for the development of new text during the task group’s second round of elaboration.

In September 2008 the CTBTO conducted its first integrated field exercise. The feedback gave further momentum to the continuing development of the OSI Operational Manual.

The Integrated Field Exercise 2008, or IFE08, was the first large-scale, as well as the most comprehensive, on site inspection exercise ever conducted by the CTBTO. It took place in September 2008 and tested selected elements of the draft OSI Operational Manual, combined in the form of a “Test Manual”.  The exercise provided feedback on many issues and will gave further momentum to States Signatories’ work on the draft OSI Operational Manual.

On-site inspection mechanisms have to be operational at entry into force of the Treaty. For the OSI Operational Manual to become the guiding document for such inspections, States Parties have to approve the final draft. This will take place at the initial session of the Conference of States Parties, 30 days after entry into force of the Treaty.

Next Chapter: Procedures