What distinguishes a 'challenge inspection' under an arms control treaty from a routine inspection?

The key distinction between a 'challenge inspection' and a routine inspection under an arms control treaty lies in the trigger for the inspection, the level of intrusiveness permitted, and the underlying suspicion of non-compliance. Routine inspections are pre-planned and conducted according to a schedule agreed upon in the treaty to verify declared activities and facilities. The inspected party knows in advance when and where the inspection will occur. The scope and procedures for routine inspections are typically well-defined and relatively limited, focusing on verifying compliance with declared activities. A 'challenge inspection', on the other hand, is triggered by a specific concern or suspicion that a party to the treaty is violating its obligations. A challenge inspection can be requested by any party to the treaty and aims to investigate undeclared activities or facilities where non-compliance is suspected. Challenge inspections are characterized by a greater degree of intrusiveness compared to routine inspections. The inspected party may have limited rights to refuse access to specific sites, and the inspection team typically has broader authority to collect samples and conduct interviews. The Chemical Weapons Convention (CWC), for instance, allows for challenge inspections of any facility where chemical weapons production is suspected, with limited ability for the inspected party to block access. The very nature of a challenge inspection implies a higher level of tension and potential for dispute compared to a routine inspection, as it suggests a breakdown in trust among the treaty parties.