As the Director of the American Central Intelligence Agency, Hot Coldman claims he was the one who set up Operation Snake Eater and convinced the higher-ups in Washington that the only way to deter a future war with the Soviets over the Virtuous Mission fiasco was to send Naked Snake to kill The Boss. Sometime after Snake Eater, Coldman was transferred to Central America to serve as the Station Chief.
Originally, he was the one who raised the "Peace Sentinel" forces in Costa Rica and sold their invasion of the country as a way to fight Soviet influence in Central and South America. Secretly, he was working on the Peace Walker project with roboticist Huey Emmerich and AI researcher " Dr. Strangelove." His theory was that Mutually Assured Destruction would not hold in the face of human influence, but an AI-controlled tank armed with nuclear missiles would make the best choice, free from bias, about how to retaliate and maintain order. Once the world knew about Peace Walker, no one would ever use nuclear weapons again, America would have all the leverage it needed, and Coldman could become the Director of the CIA once again.
When Huey learned that Peace Walker would be used to launch live nuclear missiles in a demonstration to coincide with the SALT II arms limitation talks, he began arguing with Coldman over the project, and Coldman responded by shoving him down a flight of stairs. Upon realizing that Big Boss and the MSF were going to be a threat, he decided to aim Peace Walker's nuclear missile at MSF's Mother Base. Not only would the nuclear missile destroy the base and everyone inside, but the fallout would poison the air, land and water of Costa Rica, Nicaragua and other parts of Central America. No one would retaliate, leaving Coldman free to force the affected inhabitants to build more Peace Walkers for him.
Before Coldman could carry out his plan from a US missile base in Nicaragua, Coldman's KGB contact Zadornov betrayed him and forced Strangelove to re-target Peace Walker's missile at Cuba for his own goals - framing America for nuclear assault on a Communist country and rallying Central America under the Soviet cause. Then the KGB man tried to force Paz to shoot Coldman. When she refused, Zadornov shot him anyway. Big Boss and the MSF managed to stop everyone at the last minute. However, as Coldman was being flown back to Mother Base, he used his last breath to enter in the code to make Peace Walker launch at Cuba anyway, while sending fake targeting data to NORAD that would force the US to face whether his theory of nuclear deterrence was the right one. He died without telling anyone the abort code, forcing Big Boss to take down Peace Walker the hard way.