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.
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.