What are the two keys to Mobile Defense, according to PLA notes?

• A. Emergent, short-timeline defense; two keys are extensive reconnaissance/security and seizing/fortifying key terrain
• B. Heavy reliance on air superiority
• C. Full-scale amphibious assaults
• D. Prolonged static trenches

Answer: (A)

In mobile defense, the emphasis is on a rapid, emergent defense that disrupts the attacker’s tempo rather than holding ground in fixed positions. The two keys to making this approach work are extensive reconnaissance and security, and seizing and fortifying key terrain.

Extensive reconnaissance and security means continually probing enemy intentions, routes, and marching options while keeping your own forces screened and warned. This early insight helps you deny the attacker surprise, manage the tempo of engagement, and position reserves where they can be most effective. It’s about turning information into options—knowing where the enemy is likely to push next and how they’ll be trying to mass their effort.

Seizing and fortifying key terrain means grabbing control of critical points—crossings, chokepoints, high ground, bridges, urban hubs—and turning them into strong, defendable positions. Holding or rapidly establishing these points slows the enemy, channels their movement into predictable paths, and creates favorable places for counterattacks. This isn’t about static trench warfare; it’s about using terrain to absorb and disrupt force while maintaining the ability to maneuver.

The other options don’t align with this approach: relying primarily on air superiority, conducting full-scale amphibious assaults, or persisting in prolonged static trenches would undermine the tempo, flexibility, and opportunistic counterattack posture that define mobile defense.