Can the S-400 defend an entire city? Understanding its coverage area

The Russian S-400 Triumf does not just defend a single city; it establishes a massive regional shield. Its primary 91N6E panoramic radar continuously scans a 360-degree area, detecting incoming threats up to 600 kilometres away.

When a threat is confirmed, around USD 1.25 billion, the system does not wait for it to reach urban airspace. Using the massive 40N6E interceptor missile, the battery can destroy enemy bombers and airborne warning aircraft at a maximum range of 400 kilometres.

This extreme range means a single S-400 battalion parked near a major capital can simultaneously protect dozens of surrounding towns and military bases. It pushes the engagement zone so far out that enemy aircraft are destroyed long before they can drop their payloads on civilian centres.

Urban defence requires intercepting threats from all vertical angles. The S-400 provides comprehensive altitude coverage, capable of obliterating ballistic missiles at the edge of the stratosphere at 30 kilometres high, down to cruise missiles hugging the terrain at just 10 metres.

Despite its immense power, the system cannot defy physics. Because the Earth is curved, ground-based radars cannot 'see' low-flying threats at extreme distances, creating natural blind spots where enemy cruise missiles can sneak under the 400-kilometre radar horizon.

To eliminate these dangerous low-altitude blind spots near a city, the battery deploys the specialised 96L6E radar. This unit specifically hunts for stealthy cruise missiles and drones navigating through dense urban clutter up to 300 kilometres away.

Ultimately, the S-400 is too expensive to shoot down every cheap commercial drone buzzing over a city. It forms the heavy outer layer of urban defence, handing off smaller, low-value targets to networked short-range systems like the Pantsir-S1 to ensure complete metropolitan security.