The nuclear weapons disposal facility on Shadow Moses Island was constructed to conceal the development of Metal Gear REX. Though the CNO's death was officially ruled as suicide, rumors to the contrary circulated at the time. After the cancellation of the Arsenal Ship Project in 1996 following the death of the 25th Chief of Naval Operations, the budget had freed up, allowing the REX project to proceed undelayed. DARPA funded REX's development covertly, using part of the United States' black budget. For several years, regular payments in the tens of thousands of dollars were made to the corporate account of a dummy company for which his wife ostensibly acted as a consultant. In 2002, DARPA Chief Donald Anderson was heavily bribed by ArmsTech to back the Metal Gear REX project. Likewise, the Department of Defense agreed to its development due to the defense budget being slashed by 15% and thus being forced to allow the private sector to develop their weapons for them. ArmsTech had been in a dire state financially, with the possibility of a hostile takeover becoming apparent after failing to obtain a contract on a new line of fighter jet for the U.S. Some time after Solid Snake's encounters with TX-55 Metal Gear in 1995 and Metal Gear D in 1999, an attempt to carry out a Metal Gear project within the United States had been planned but was officially scrapped yet convinced the private weapons company ArmsTech that building one for the U.S. The designs also served as the inspiration for the Chrysalis, Peace Walker, and Metal Gear ZEKE in the early 1970s as well as Metal Gear Sahelanthropus in 1984. Non-'Metal Gear Saga' information ends here. The development of REX itself was foreseen in a psychic premonition by Elisa and Ursula during the San Hieronymo Incident in 1970. The duplicate designs would later served as the inspiration for the Intercontinental Ballistic Metal Gear. Warning: The following information is from outside Hideo Kojima's core 'Metal Gear Saga.' Its canonicity within the continuity is disputed, therefore reader discretion is advised. The Soviets also researched ways to launch an untraceable missile since 1964. Later, triple spy Ocelot also stole and delivered duplicate designs to his CIA superiors. Drunk and bitter, Granin sent his designs to an American colleague, revealing this to CIA operative Naked Snake during Operation Snake Eater. However, Colonel Volgin of GRU rejected his ideas in favor of Nikolai Stepanovich Sokolov's Shagohod. In the early 1960s, Soviet scientist Aleksandr Leonovitch Granin created designs for a REX-like bipedal tank.

Granin's designs and notes for what would ultimately become Metal Gear REX, 1964.

4.11 Metal Gear Solid V, Online and Survive.

4.5 Metal Gear Solid 4: Guns of the Patriots.

4.4 Metal Gear Solid Mobile and Portable Ops Plus.

4.2 Metal Gear Solid 2: Sons of Liberty.

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