Metal Gear Solid: Metal Gear Rex Plastic Model Kit

REX was the ultimate Metal Gear, as it was not only capable of delivering a nuclear weapon both to and from any point on the globe, it could do so "undetectably" and "untraceably." All previous Metal Gears were merely mobile ground-based launch systems for nuclear missiles, little more than the land-based equivalent of ballistic missile submarines.

REX utilized a rail gun, which fired much smaller projectiles without chemical propellants and contained stealth technology - factors which made them virtually invisible to radar. It thus fatally undermined the 'no first strike' principle of Mutually Assured Destruction - whoever controlled it could launch a nuclear attack at any target at any time, with no warning before impact. In addition, its missiles also have enough power to destroy underground bunkers, a lesson that was learned from the Gulf War.