Iran’s underground “missile cities” hidden within mountainous terrain are emerging as a powerful example of modern defensive warfare. Despite repeated U.S. airstrikes targeting tunnel entrances and surface infrastructure, reports suggest these deeply buried networks remain largely operational. Built into natural rock formations and connected through complex tunnel and rail systems, these facilities allow Iran to maintain missile production, storage, and launch readiness. The development highlights the growing importance of hardened underground military infrastructure and raises questions about the limits of precision airpower in modern conflict.