---
title: "CTBTO International Monitoring System (IMS)"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "CTBTO International Monitoring System"
aliases: ["IMS","Ring of Five","Ro5"]
first_seen: "2026-07-09T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["radionuclide monitoring","Comprehensive Nuclear-Test-Ban Treaty Organization","sensor vs inspector verification","Nyonoksa/Nenoksa radiation accident (2019)","Burevestnik (9M730 Skyfall)"]
---


The global sensor network built to detect clandestine nuclear explosions, including a radionuclide leg that hunts trace atmospheric isotopes (notably xenon) as evidence a test occurred even when otherwise contained. The vault's verification cluster keeps running into this network from different angles without yet having a page to describe it: as the sensor-based counterpart to on-site inspection regimes, as a detector confounded by civilian medical-isotope production, and — closest to home — as the infrastructure that specifically sat astride the Nyonoksa accident's modeled plume path and went dark for reasons a senior Russian official's own words suggest were not technical.

## References
- [[claim-ctbto-radioxenon-monitoring-confounded-by-medical-isotope-production]] · [[claim-two-verification-regimes-sensor-vs-inspector-govern-the-same-fissile-material-lifecycle]] · [[claim-ctbto-ims-stations-nyonoksa-plume-path-went-dark-not-technical]] · [[claim-spykman-2021-null-result-burevestnik-radionuclide-search]]
- Related hubs: [[entity-nyonoksa-nenoksa-radiation-accident]]