India, Nov. 4 -- Deterrence rests on an adversary's belief that aggression will fail or invite costs greater than its expected gains. For India, this calculation has long been shaped by Pakistan, China and the possibility of escalation between nuclear-armed states. Emerging technologies are complicating that calculation. Drones, precision weapons, cyber operations and electronic warfare allow adversaries to probe defences and impose costs through methods that can be difficult to attribute or contain.

India's response must connect military preparedness with the ability to sustain essential services and recover from disruption. Yet defensive success, resilience and deterrence are distinct. Intercepting a missile demonstrates capability. Re...