# Perimeter Defense: How GLMZ Protects Its Borders

## Overview

GLMZ is a corporate city-state in a world of corporate competitors. Its borders are defended not by national armies but by a layered defense system designed to deter, detect, and defeat any attempt at unauthorized entry or military aggression. The defense system is operated by Arcturus under contract to the governance consortium and represents the largest single expenditure in the city's security budget.

## Defense Layers

### Layer 1: Sensor Perimeter (50 km radius)
The outermost defense layer is a network of sensors — ground-based radar, acoustic arrays, seismic monitors, and orbital surveillance feeds — that monitor a 50-kilometer radius around GLMZ for approaching threats. The sensor network detects vehicles, personnel, aircraft, and drones at ranges that provide 20-30 minutes of warning before a ground-based threat reaches the city perimeter. The sensor data is processed by AI systems that classify threats, predict approach routes, and recommend responses.

### Layer 2: Active Defense (5 km radius)
The active defense layer deploys automated weapon systems: anti-aircraft gauss batteries, ground-based railgun emplacements, drone interceptors, and electronic warfare systems that can jam, spoof, or hijack approaching autonomous systems. The active defense layer is designed to defeat military-grade threats — armored vehicles, combat drones, and organized infantry formations.

### Layer 3: The Wall (perimeter)
The city's physical perimeter — the Water Wall on the lake side and reinforced barriers on the continental side — provides the final physical obstacle. The Wall is monitored by sensor arrays, patrolled by autonomous security drones, and defended by automated weapon positions that activate in response to perimeter breach.

### Layer 4: Sentinel-Guard-88
The sentient perimeter defense robot operates across all three outer layers, maintaining vigilance with the paranoid awareness of a military AI. Guard-88's selective enforcement — maintaining full vigilance against hostile threats while selectively disabling detection for refugees — creates a perimeter that is simultaneously impenetrable to armies and permeable to the desperate.

## The Threat Landscape

GLMZ's perimeter defenses are designed against three threat categories:

**Corporate military action**: Armed aggression by a rival corporate entity. The Border War of 2163 is the reference scenario. Current defenses are designed to defeat a Bellerophon-scale attack with 90% confidence.

**Insurgent action**: Small-scale attacks by non-state actors — criminal organizations, ideological extremists, or corporate-sponsored deniable forces. The perimeter's sensor network is optimized for detecting small-group infiltration, and the active defense layer includes anti-personnel capabilities alongside anti-vehicle systems.

**Autonomous threats**: Unmanned attack systems — drones, robotic combat platforms, and the autonomous weapons that any well-funded organization can deploy. The electronic warfare component of the defense system is specifically designed to counter autonomous threats, using signal jamming and AI countermeasures to disable attacking systems before they reach the perimeter.