Peace Walker Incident

The Peace Walker Incident was a series of military skirmishes fought between the CIA Peace Sentinel and the Militaires Sans Frontières mercenary group in November 1974, mainly taking place within Central America. The incident concerned the development of the Peace Sentinel's Peace Walker Project and the MSF's efforts to prevent its completion.

"Clients"
Having left his military career in the U.S. behind him, Snake, a.k.a. Big Boss, founded the Militaires Sans Frontières, and stationed his troops on the Barranquilla Coast of Colombia. During a combat training session on November 4, 15:42, MSF subcommander Kazuhira Miller returned to their base camp with two visitors, reassuring Snake that they were not CIA and had not been followed.

Snake and Miller then met with the two guests in their office. Ramón Gálvez Mena, a distinguished scholar for the Costa Rican government, and his student, Paz Ortega Andrade, were seeking the MSF's help in repelling an unknown armed force that had entered their country. The local authorities had claimed that they were a multinational security firm hired by the Developmental Corporation of Costa Rica, though Gálvez believed this to be false due their advanced weapons and equipment, hinting that &quot;la cia&quot; may be involved. Since Costa Rica itself was unable to bear arms due to its peace constitution, Gálvez wished to hire the MSF as a deterrent, offering them a forward operating base off the coast of the Caribbean, and a chopper for transport, as payment. The government would also provide aid to them, unofficially.

Believing that military force was unlikely to solve the issue, and that the MSF were not simply "dogs of war," Snake was reluctant to accept Gálvez's offer. Entering the discussion, Paz proclaimed her overwhelming desire for peace in her country, revealing a passionate hatred for war, though Snake simply apologized to the young girl. A few days prior, Paz had been captured by the mysterious security company near a supply port north of Puerto Limon, while searching for a lost friend. She was subsequently imprisoned and tortured, though she was later able to escape. After describing these events to Snake, Gálvez then stated that they were aware of his identity as Big Boss, which was why they had come to him.

At 20:31, after some further discussion away from the two visitors, Miller expressed the view that Gálvez's offer was an opportunity to expand the Militaires Sans Frontières and put down some roots, though Snake was not entirely convinced. The two also began to suspect that Gálvez was actually working for the KGB, and that by allying themselves with him, they'd be making an enemy of America. Confronted with this knowledge, Gálvez dropped his facade and explained of his mission: since the Soviets wished to establish a socialist stronghold in Central America, he had been ordered to hire the MSF to investigate the CIA's suspicious activities and force them out of Costa Rica. Having concealed any KGB affiliation from Paz, Gálvez played back a tape cassette that her friend had recorded prior to their capture. Snake was shocked to hear the voice of his supposedly deceased mentor, The Boss, to which Gálvez confirmed from voiceprint analysis. With Gálvez threatening to burn the tape, using the cigarette lighter from his prosthetic right hand, Snake finally relented, though he claimed he would be doing it for Paz.

"The Spear"


Six days later, on November 10, Snake arrived on the coast of Costa Rica at Playa del Alba, after the MSF settle aboard the offshore plant provided by Galvez, dubbed Mother Base. With radio support from Miller, Snake infiltrated the jungle where he evaded the patrolling CIA mercenaries. At the supply depot, he interrogated a radioman who had been directing cargo to Mt. Irazu, before knocking him unconscious with his stun rod. Snake then witnessed a strange VTOL aircraft passing overhead, before finding a map concerning the security company's bases in the region. Noticing the unusual amount of radiation film badges at the depot, and recalling the radioman's earlier conversation regarding "spears," Snake and Miller become alarmed that nuclear weapons were apparently being shipped into the country. This act would constitute a violation of the Tlatelolco Treaty, ratified by Costa Rica in 1969, which forbid it from the use, storage, or transport of nuclear weapons.

"Fearless"
Requiring more intel on the lay of the land, and to verify the presence of nukes in the region, Miller suggested that Snake ally himself with the local Sandinista guerillas, who had fled the Somoza regime in neighboring Nicaragua. Meanwhile, Miller assured Snake of the ongoing repairs to the previously abandoned Mother Base, and Paz offered to provide additional radio support from her school at Ciudad Colón. Miller then informed Snake that the Sadinistas' hideout in El Cenegal was under attack and that he should hurry.

Snake traversed the El Cenagal jungle to the northwest, bypassing a ravine and passing through the swamp near the Rio del Jade. He arrived at the FSLN's boathouse hideout and neutralized the occupying security detail, before making contact with the hidden Sandinistas and their comandante, Amanda Valenciano Libre. Confirming that the security firm were indeed CIA, Amanda suspected that they were going to stage a coup similar to the one in Chile. Amanda claimed that their advanced hardware and multiple bases could not simply be to eradicate their group (the amount was comparable to Da Nang), and that something of more importance must be occurring. She told Snake of a mercenary base to the north, located in an abandoned factory, which had once served as a front for a drug production plant, provided by the KGB to help finance their revolution. A transport boat with mercenaries on board had also been heading upstream towards Irazu.

"Little Brother"
Amanda's Sandinistas were suddenly attacked by the aircraft Snake had witnessed earlier, revealed to be an unmanned weapon, accompanied by several "kidnapper" drones. Though a few drones were destroyed by Snake's LAW, one was able to capture Amanda's younger brother, Chico, with its grappling hook and escape. The Sandinistas then gave chase as the unmanned aircraft and drones departed, with Snake choosing to follow after enemy reinforcements were deployed to the area. Proceeding to the banana factory that Amanda had mentioned earlier, Snake was forced to neutralize an enemy LAV-Type G and the heavily armored soldiers accompanying it. After departing the banana plantation, Snake found Amanda in the jungle, where a kidnapper attempted to abduct her. Snake helped her to get free, though she was injured from the fall, breaking one of her legs in the process of landing.

Afterwards, Amanda told Snake of a prison in the mountains, which was where Chico was most likely to be located. Snake then requested that she join the MSF aboard Mother Base until she could heal up. Realizing that they needed a guide to help track down the nuclear weapon shipment, Snake infiltrated the prison facility in Camino de Lava in order to rescue Chico, who was intimately familiar with the route into the mountains. Successfully locating Chico, the twelve year old boy informed Snake of the shipping route used by the CIA mercenaries: cargo from the harbor was first transported by barge though the marshes; it was then taken by train though a coffee plantation; then finally loaded onto trucks to ship to the other side of Mt. Irazu, via an underground tunnel. Chico had never ventured any further, since the area was supposedly guarded by a spirit, which he referred to as "el basilisco." Upset that he had betrayed his compas while being interrogated, Chico asked Snake to kill him. Snake refused, demanding instead that Chico prove his strength by fighting with him and becoming a new man. Chico then joined his sister aboard Mother Base to support the MSF in their mission.

"Tank Corps"
Snake then headed to the jungle train depot, east of the coffee plantation, to stop the delivery of nukes. Rescuing several FSLN prisoners along the way, Snake reached the depot, though he was too late to prevent the nukes being transported via truck through the underground tunnel. He was then forced to neutralize an enemy T-72 Ural tank that had spotted him, along with its escort unit, after the tank demolished the tunnel entrance.

Forced to proceed via an alternate route via Los Cantos, Snake eventually arrived at Fuerte la Ladera. Evading the enemy soldiers stationed at the old fortress, Snake reached the entrance to their base, hidden within a crater. Infiltrating a garage, Snake identified the truck he had seen earlier from its license plate, though the nukes had already been offloaded.

Attempting to locate the nukes within the facility, Snake overheard an argument between wheelchair-bound engineer Huey Emmerich and the CIA Station Chief of Central America, Hot Coldman. Coldman intended to purposefully launch a nuclear warhead using Huey's creation, in order to prove its effectiveness in regards to nuclear deterrence, and return to his former position as CIA Director. Huey, however, was unconvinced and refused to cooperate with his employer any further. The argument then turned violent, with Coldman shoving Emmerich down a stairway before departing.

"Pupa"
Helped back into his wheelchair by Snake, Huey frantically told him of the impending nuclear launch. Rushing to the large open-top hangar, Snake witnessed the removal of a tarp-covered device by the unmanned VTOL aircraft, accompanied by a Hind D gunship. A tank, notably similar in appearance to the Soviet Shagohod, suddenly entered the area, and attacked Snake. Equipped with an AI pod on its frame, Huey warned Snake that the vehicle was also an unmanned weapon, codenamed Pupa. With Huey's advice, Snake was able to defeat the Pupa and put it out of commission.

Huey later informed Snake that the Pupa was a prototype AI weapon, similar to the VTOL aircraft Chrysalis, and a treaded type known as Cocoon. Led by disgraced former DCI Hot Coldman, the security company operating within Costa Rica, known as the Peace Sentinel, had used the Irazu facility to develop the AI weapons' frames. The nukes that Snake had been pursuing were now loaded onto the machine that was airlifted from the facility. Codenamed Peace Walker, the bipedal machine was a mobile unmanned nuclear platform, and the end result of the Peace Sentinel's AI research.

"Cold Principle"
The aim of the Peace Walker project was to develop an automated, fail-deadly, nuclear launch system, stealth-shielded from radar and satellites to evade any pre-emptive strike. Its purpose was to launch a retaliatory strike at an appropriate target, without human input, in the event of a nuclear attack, overcoming the inherent uncertainty in human decision making. Huey had proposed that the weapon have a bipedal design in order to traverse the difficult terrain of Central America, where several units were to be deployed. Snake then realized that Peace Walker was the "el basilisco" that Chico had witnessed, and that Peace Walker was in essence a similar concept like Metal Gear that was described to him by Aleksandr Leonovitch Granin ten years ago.

Though initially believing in the maintenance of peace through nuclear deterrence, Huey had been unwilling to allow Coldman to demonstrate the weapon's power by carrying out an actual nuclear attack. Demanding to know where the nukes were headed, Snake was told they had been taken to the border, and that the final test would take place in five days. Huey suggested that Snake locate another of Peace Walker's AI researchers, Dr. Strangelove, who had created the weapon's high-level decision-making AI, the Mammal Pod. Huey then considered abandoning his research, though Snake convinced him to join "Outer Heaven" instead, as part of the MSF's R&D team aboard Mother Base. Agreeing to this, Huey speculated that with enough resources, the MSF could build their own bipedal mech, to help thwart the Peace Walker project.

"Air Strike"
On November 19, Snake set out for the AI facility, avoiding the heightened security in Selva de la Leche, before arriving at Catarata de la Muerte. A Hind A, accompanied by several troops were waiting for Snake in the area, forcing him to neutralize them all. Emerging victorious, Snake continued on to Selva de la Muerte, bypassing more security, until he eventually reached the Ruinas de Xochiquetzal.

While travelling through the ruins, Snake found a distressed woman resting by a tree, who became startled by his sudden appearance. Snake reassured the Frenchwoman, an ornithologist named Cécile Cosima Caminades, that he would not harm her, and offered her a mate. Having visited Costa Rica a week earlier to observe the native quetzal, Cécile had accidentally recorded the voices of two women conducting a test exercise, with her portable cassette player. She had subsequently been captured by armed soldiers, then blindfolded and imprisoned, though she was well cared for by one of the women she had previously overheard. Stealing an ID card, she had recently escaped into the jungle, before succumbing to exhaustion, barefoot and with no supplies. Realizing that she must be Paz's lost friend, whose tape was in the MSF's possession, Snake had her transported back to Mother Base via Fulton recovery, where she could either stay and help, or return home.

"Entry Gate"
Proceeding to the AI facility, which was hidden within an ancient Mayan temple, Snake discovered that the ID card provided by Huey would not grant him access. He then contacted Cécile back at Mother Base, who told him of an orange-jacketed guard that had confiscated her own stolen ID card during her escape attempt. Stationed in an area in which she heard quetzals singing, Cécile helped Snake to identify the guard and secure the card.

Later, Miller informed Snake that the tape back at Mother Base had indeed belonged to Cécile, but discovered that she had never even met Paz before. Choosing to settle the matter later, Snake gained access to the grounds of the research facility, where he encountered a white Andalusian horse; the same breed as that which had belonged to The Boss. Confronted by a woman in a red coat and sunglasses, Snake correctly identified her as Dr. Strangelove, who accused him of coming to destroy her research. Strangelove held a great deal of resentment towards Snake, due to his assassination of The Boss ten years earlier. She had been waiting to meet her killer, who had chosen loyalty to a shadowy country over the mentor that had made him who he was. Feeling abandoned after The Boss's death, Strangelove was desperate to learn the answers from the woman she had once loved, and she had attempted to bring her back to life in the form of the AI she was currently developing. Though he remained suspicious of her intentions, Snake was intrigued by her knowledge of The Boss, and followed her into the lab. There, he was presented with the cylindrical shell-encased AI, the Mammal Pod.

In return for her participation in the Peace Walker project, Strangelove had demanded that the CIA grant her access to all information regarding The Boss: her personal history; military records; physiological data; correspondence; files on every single operation she had participated in, every decision she had made, and every emotion she had felt during her lifetime. Believing The Boss to be the finest rational mind with which to model the MAD-based AI, Strangelove knew that it would be capable of selecting the most suitable targets for nuclear retaliation, however painful the decision might be. However, her true goal was to clear The Boss's name, by learning why the legendary hero was forced to betray her country, and why she had been killed by her most beloved disciple. Snake denied wanting to know The Boss's last will, calling her a traitor, to which Strangelove challenged him to destroy the AI, and extinguish her noble soul once more. Beckoned by the voice of The Boss, Snake entered the AI pod, though he was unable to destroy it due to the AI's haunting words, forcing him to recall his past in Tselinoyarsk, before passing out.

"Chrysalis"
Awakening on the AI facility's grounds, Snake saw a Hind carrying away the AI pod. The Chrysalis AI weapon then emerged from behind the temple, and Snake was forced to destroy the aircraft. Shortly thereafter, Miller contacted him to confirm the location of Peace Walker's final testing area, identified with Huey's help: an underground base disguised as a rock quarry 15 miles to the north of the lab. Accused of being unable to come to terms with his past, regarding The Boss, Snake swore to Miller that he would destroy the AI upon their next encounter, due to Peace Walker's imminent completion. He also began to doubt what exactly The Boss's intentions were after his meeting with Strangelove, believing that EVA's debriefing for Operation Snake Eater may have been a coverup.

"Cocoon"
Using the Boss's old horse, Snake traveled to the quarry on November 21. Abandoning the horse, Snake reached a mining pit where he observed Peace Walker itself descending, via cargo elevator, into the underground base for final testing. As he made his approach, Snake was spotted by a kidnapper drone, triggering an alert that sent Peace Sentinel troops out to kill him. After the entire unit was neutralized, the Cocoon AI weapon then entered the pit to finish Snake off, forcing Snake to destroy the gargantuan attack craft. Shrapnel from Cocoon's destruction damages a nearby electronic door, allowing Snake access to the base.

"Facility"
Reaching Peace Walker's hangar, he saw Strangelove's team taking a break from preparing the unit, and slipped through to the Mammal Pod. Snake then interrogated the Boss AI about Operation Snake Eater, but unable to gain any answers from it, he prepared to destroy it. The AI pod suddenly opens up, with Strangelove, Coldman, and several troops surrounding him. Coldman explained that the deployment of Peace Walker was part of a plan to re-establish U.S. superiority that had faded in the aftermath of the Cuban Missile Crisis and the various arms control treaties established ever since. Coldman also admitted to being the mastermind of Operation Snake Eater, and implied that he had been relocated to Central America as a result. Seeing an opportunity to attack, Snake engaged several of the guards in CQC, grabbing Strangelove's ID card in the confusion, before being subdued.

Snake later awakened in a prison cell, where he was tortured by Strangelove on whether The Boss had truly died for her country or if she was indeed a traitor. Snake's refusal to talk, however, gave her the clues she needed to complete the Mammal Pod's programming. After falling unconscious, Snake came to in a cell, and used Strangelove's ID card to free himself. Recovering his gear, Miller informed Snake that he had been unable to contact Paz, and that she and Galvez were not at her school either. Suspecting that Coldman may be behind her disappearance, Snake returned to Peace Walker's hangar, where his suspicions were proven correct upon encountering said Station Chief and a captured Paz.

Coldman proudly told Snake of the Mammal Pod's completion, thanks to his interrogation at the hands of Strangelove. He then revealed that Peace Walker's first target would be MSF's Mother Base in the offshore area of the Caribbean. The trade winds would then scatter the nuclear fallout all throughout the region, causing fish and crops to die out, leaving many free hands to contribute to Peace Walker's mass production. Before the test, Coldman intended to first demonstrate to the White House Peace Walker's all-terrain capabilities, by having it travel the Caribbean Coast on its own, traversing both communist and guerilla territory. Coldman then departed with Paz, with Snake becoming distracted by Peace Walker's sudden activation, which began to ascend aboard the cargo elevator to the mining pit above.

"Take Down"
Climbing out of an emergency escape hatch above ground, Snake immediately fired upon Peace Walker, whereupon the Mammal Pod entered self-defense mode and retaliated. The bipedal Peace Walker then opened up with its smaller weapons launchers and flamethrower. After a grueling fight, Snake dealt sufficient damage to the machine to cause its momentary collapse to the ground, and its AI to begin behaving erratically. Coldman's Hind D then fired a few rounds at the Mammal Pod, causing Peace Walker to enter a quadrupedal formation and begin following the gunship across the mountainous forests. With The Boss's horse returning to his aid, Snake gave chase to Peace Walker, evading its missile attacks as trees collapsed all around them. However, as Peace Walker approached the Nicaraguan border, Snake's horse lost its footing on the steep slopes. Though Snake was relatively unscathed, the horse was gravely wounded and he was forced to shoot the animal dead. Scaling the hillside himself, Snake watched helplessly as Peace Walker crossed the Rio San Juan.

By kidnapping the MSF's client, Coldman hoped to prevent the group's interference with Peace Walker. Speculating that he was aware of her connection to the KGB, via Galvez, Snake and Miller assumed he would also interrogate her on the Soviets' plans to disrupt the weapon. Meanwhile, Amanda had her Nicaraguan compas of the Guerra Popular Prolongada track Peace Walker towards a U.S. military supply base on the southeastern shore of Lago Cocibolca. To cross the border, Amanda told Snake of a route that the FSLN use to cross by boat, and arranged an introduction with the captain.

With information provided by Huey, the MSF realized that Peace Walker would launch its nuke from the U.S. base following two days preparation, which would coincide with the upcoming U.S.-Soviet SALT-II (Strategic Arms Limitation Treaty) talks in Vladivostok. Wondering whether Coldman planned to disrupt the negotiations, or use it as a bargaining chip, the MSF made preparations to infiltrate the base and prevent the launch.

"Dead Ahead"
On November 23, Snake traveled to Nicaragua by gondola, heading west of the river until he reached the northern bank and was assisted by a guide to get close to the U.S. missile base. Snake then disguised himself as a crate and managed to hitch a ride in the back of a cargo truck through the back gate. Miller informed Snake of an airfield on the other end of the base, which was where Peace Walker would launch, along with a communication tower ahead of him where it would be controlled from. Snake briefly considered calling an evacuation of Mother Base, which Amanda and her FSLN unit had already done, though the rest of MSF decided to stay behind, confident that Snake would prevent the launch. However, Miller decided to prepare a backup unit to aid him, just in case.

Commencing his infiltration, Snake discovered kidnapper drones and Soviet soldiers patrolling the American base, and was mystified by their presence. Entering a security recording room, Snake found Paz on one of the video monitors, who informed him that Coldman was headed for the comm tower in order to input the final data for Peace Walker's launch. Sirens suddenly sounded throughout the base, and Snake was forced to fight his way to the comm tower, with Miller and the MSF heading to Nicaragua to aid him, via a squadron of helicopters and gunboats. Reaching the tower, Snake neutralized a Hind D and an entire enemy unit that was protecting the entrance, before proceeding inside.

"Boot Sequence"
Inside the comm tower, Snake encountered Coldman and Paz, but was quickly surrounded by dozens of Soviet soldiers. Coldman proclaimed that Snake was too late, having already input false data regarding a Soviet nuclear attack on the United States mainland. Since Peace Walker was solely a deterrent, it was incapable of commencing a pre-emptive nuclear strike, so it was necessary to trick Peace Walker's AI into retaliating to a perceived threat, which would select an optimal target from a pre-defined list. The false data had also been reverse-engineered to have Peace Walker inevitably choose Mother Base as its target. Coldman believed that Peace Walker would be the first and last nuclear retaliation of the Cold War, and that it would be the only way to ever come close to true peace. As he prepared to input the confirmation code via a briefcase handcuffed to his arm, Snake pointed his rifle towards him, ignoring the surrounding soldiers, until they were interrupted by the appearance of Professor Galvez.

Snake and Paz both realized that Galvez, real name Vladimir Alexandrovich Zadornov, had been in league with Coldman all along. However, Zadornov then announced the successful occupation of the base by his troops and the soldiers present subsequently pointed their weapons towards Coldman. Having previously supplied technology to the Peace Sentinels, in exchange for land and soldiers, Zadornov had planned to take Peace Walker for himself and launch a nuclear strike at Cuba instead. A nuclear weapon launched from a United States missile base, located in a country with a pro-American regime, towards one of the Soviet Union's greatest allies, would cause anti-American sentiment to spread throughout Central America, splitting North and South America apart, and bringing the Soviets one step closer to winning the Cold War. Coldman was outraged at Zadornov's betrayal.

Zadornov then placed his gun into Paz's hands and ordered her to shoot Coldman, reminding her of the torture she had suffered at the supply facility. Coldman apologized to her and Paz could not bring herself to fire at him. Grabbing Paz's hands, Zadornov pulled the trigger of the gun and shot Coldman twice in the chest, though he deliberately avoided a killing blow. Zadornov then forced him to place his red diskette into the nuclear launch briefcase and ordered Strangelove to change Peace Walker's target to Cuba, threatening to crush her "beloved" should she resist. Finally turning to Snake, Zadornov remarked that he was a true comandante, having taken a ragtag group of rebels and children and turned them into a formidable army, providing additional momentum to the revolution in Nicaragua. His death at the "CIA's hands," similar to Che Guevara before him, would strengthen the Sandinistas' resolve in overthrowing the pro-American regime, with the nuclear launch at Cuba being the last straw. After an announcement that the Mammal Pod's data entry had been completed, Zadornov told Snake that he would die just like The Boss died: as an eternal fraud.

However, before he could execute Snake, both the MSF the FSLN stormed into the control room and took out the Soviet soldiers. Amanda then forced Zadornov onto his knees, proclaiming that the Sandinistas would no longer be puppets for the KGB, and that they would win their own victory. Having accomplished their goal in returning to Nicaragua with Snake's help, the Sandinistas began to chant "Vic Boss!" in celebration.

Soon afterwards, the MSF began their return to Mother Base, with Zadornov and an injured Coldman in their custody. Telling Miller that he would catch up later, after he disposed of The Boss AI, Snake was confronted by Strangelove. She informed him that she had only wished to learn the truth about The Boss by bringing her back as an AI, and that he should speak with it to learn of it himself. She also offered her apologies for having tortured Snake earlier, and thanked him for eliminating the Peace Sentinels.

"Uninterrupted Signal"
Meanwhile, Paz cried aboard an MSF chopper due to her ordeal at the base, with Miller remarking that aiming a weapon alone does not make it a deterrent. He also reminded Paz of her role as an "angel of peace" and that she should leave the guns to MSF, their mission in Costa Rica now complete. However, Coldman, despite dying from blood loss, was able to input a code into the nuclear briefcase before Miller could stop him, laughing as he did so. As a result, Peace Walker became active, preparing for the nuclear launch at Cuba, with Coldman telling the group that the input false data would also be relayed to NORAD. Miller quickly informed Snake of this development, since the MSF were unable to block the MLF signal. Since the false data was designed to be indistinguishable from that of a real Soviet attack, Washington would be forced to consider nuclear retaliation, though Coldman was confident they would be unable to do so, due to human nature. Peace Walker's AI, however, would have no qualms regarding a retaliatory strike, thus proving its effectiveness as the "perfect deterrent."

With the U.S. President and Vice President in absence, due to the SALT-II talks, the Legislative Branch would be granted nuclear launch authority, more specifically the Speaker. Believing the false data to be reliable, NORAD initiated DEFCON 3 and contacted SAC to prepare for an emergency meeting. Huey, hacking into Peace Walker's data transmission, relayed these developments to the MSF, though Coldman remained convinced that Washington would order no retaliation. Miller demanded that he stop Peace Walker, since only he knew of the abort code, but Coldman refused. Attempting to make the V-for-Victory sign, Coldman exclaimed the word "Peace" before finally passing away.

Snake immediately set out to destroy Peace Walker, to both prevent the nuclear launch and stop the false data transmission. After a lengthy battle, Peace Walker's drive system was damaged, and the launch was prevented, though the data uplinks still remained intact. Huey then informed Snake that BMEWS were continuing to track the false targets on radar and that the DSP satellite status was green. Meanwhile, the Chairman of the Joint Chiefs of Staff, a representative of the Secretary of Defense, and various members of Congress arrived at the NMCC. A NORAD Operator confirmed from the data that there were 1,500 ICBMs crossing the North Pole and were targeting the West Coast, commanding that they go to DEFCON 2 and prepare launching ICBMs towards the Soviet Union.

As a fully autonomous system, Peace Walker's command authorities were located inside the Mammal Pod, unlike the other AI weapons Snake had fought. Mammal Pod's outer casing was also designed to be as strong as a nuclear bomb shelter, making his weapons ineffective. Huey then pointed out that sinking Peace Walker into the nearby lake may disrupt the sensitive electronics of the AI, since the pressure at its depths may cause water to penetrate the damaged frame. However, Miller realized it would be impossible to lift the 500 ton behemoth. Back at the ECR HQ, the members were unable to contact the President and after much frantic argument, they agreed on nuclear retaliation. Realizing that Coldman had been wrong, Snake demanded that Huey patch him through to the Pentagon.

Making contact with the Chairman, Snake ordered him to abort the retaliatory strike, telling him of the false data leak executed by the now-dead CIA Station Chief of Central America. As proof of his identity as Big Boss, Snake described to him the events of his secret debriefing by former President Johnson, following Operation Snake Eater, to which the Chairman had been in attendance as the Army Chief of Staff. Convinced of Snake's truthfulness, the Chairman told everyone that the Soviet missiles were fakes and that it was indeed Big Boss who had contacted them. However, some members remained skeptical, with one officer pulling a gun on the Chairman after he attempted to call off the retaliatory strike.

"Peace Walker"
Just as all hope seemed lost, the Mammal Pod opened of its own accord, allowing Snake access to The Boss AI in order to remove all of its memory boards. However, the data uplink remained in effect. Meanwhile, the ECR Officer holding the Chairman at gunpoint declared his authority to call the nuclear strike and he did so, remarking that deterrence was nothing more than a fool's dream. At the missile base, Stranglove told Snake that Peace Walker's second AI, the Reptile Pod, must have overtaken the functions of the Mammal Pod. Snake, in desperation, tried to damage Peace Walker as much as possible, and the machine seemingly malfunctioned, then began to stand upright. The AI then began to playback The Carpenters' "Sing," which had been a hit in 1973, using the voice of The Boss herself via its speech synthesis system. Peace Walker then began to enter the lake, causing Strangelove to remark that she was trying to drown herself to stop the data transmission.

The missiles on NORAD HQ's radar then disappeared, and were replaced by Peace symbols. Huey deduced that, in a similar function to the human brain, Peace Walker must have used functional compensation to take over its tasks, as a result of the Mammal and Reptile Pods essentially acting as one. Strangelove wondered if her memories remained in her through the song. Huey then mentioned that it was not thinking clearly, and was instead using its heart. Miller then stated that The Boss's innocence had been proven, and requested for Snake to listen to her song. Strangelove then realized and understood why The Boss had done what she did ten years ago: when she went into space as part of the Mercury Project, she saw a beauty other than war. She put down her gun and instead chose to sing. They would all hear her singing, and she sacrificed everything to have her will live on. She couldn't achieve it, but she still sang, hoping for the illusion called peace that could not be found. Snake, after mirroring his salute ten years ago at The Boss's grave, then removed his bandana, where it was lost to the wind.

Afterwards Snake held a brief conversation with Kaz in which he declared that he had again found himself and wished to live his life differently from that of The Boss. He felt that she had betrayed him and everything she did as a soldier by lowering her gun and surrendering her life merely for her country. Snake finally requested that he be known as "Big Boss" from then on.

"Zero Allies"
After the events in Costa Rica and Nicaragua, Paz was evicted from her school dorm, since her scholarship had come from Zadornov, so Snake allowed her to stay at Mother Base to help out. Since Coldman's death left Strangelove without a job, Snake also accepted her and she began working on the Militaires Sans Frontières's own AI weapon, called Metal Gear ZEKE, alongside Huey. The mech was later armed with Peace Walker's nuclear warhead, which was recovered from the bottom of Lago Cocibolca, in order to provide a nuclear deterrent for the expanded Mother Base. Zadornov also escaped his cell several times, forcing the MSF to find and recapture him. On the last time, Snake found him at the shooting range and killed him in self-defense after Zadornov tried to gun him down. Dying, Zadornov then launched his prosthetic hand at Snake, revealed to be a rocket-powered projectile, after mentioning that his work was done, though he again missed his target. Snake was suspicious because Zadornov's numerous escapes pointed to an inside job. Kaz alerted him about ZEKE suddenly moving out of its hangar and rising to the surface of Mother Base.

Snake arrived on Mother Base's deck to discover that Paz was manually operating the ZEKE unit. Miller was unable to shut it down remotely, with Paz revealing that she had made modifications to ZEKE while Zadornov had diverted their attention with his multiple escape attempts. She then announced that she was taking it back to "their" leaders, Cipher, and that her real name was Pacifica Ocean. Her portrayal as an ambassador of peace had simply been an elaborate ruse, and that the real Peace Walker Project would soon be fulfilled. Pacifica accused Snake of having taken the wrong path, regarding his parting ways with his former FOX commander and friend Zero two years earlier. The two men had been unable to come to terms with their sorrow over The Boss's death, so they had each decided to carry on the will of their hero. However, they could not agree what that will was, so they had split up and become bitter enemies. Pacifica then demanded that Snake follow the will of Cipher.

With the Cold War nearing an end, the age of electronic intelligence would come to the fore, and Cipher planned to unite the various agencies of the intelligence community under a single will. Cipher would then gather information with the intent of guiding the world and its people's minds, while the populace remained blissfully unaware. Ultimate control would provide the illusion of peace, and a "world without borders" would arise, accomplishing what The Boss had apparently long sought for. By obeying Cipher, the Militaires Sans Frontières would act as a deterrent against forces that would threaten the development of this new world order, distracting the old order's eyes with Snake's charisma and military prowess.

"Koi no Yokushiryoku"


Reasurring Snake that he would be allowed to retain control of MSF and ZEKE, Pacifica beckoned for him to accept Cipher's offer. Snake denied her accusation that he was afraid to abandon his life's calling, as The Boss had supposedly done, and refused the proposal. Rescinding the offer, Pacifica then sought to launch a nuclear strike at the U.S. East Coast, then frame the MSF as an extremist cult. Snake took on and destroyed ZEKE, but before it was destroyed, Paz warned of Snake becoming an international criminal in the decades ahead. ZEKE then exploded and Paz was thrown by the force of the explosion into the ocean. Big Boss can only express remorse at having to fight Paz. The remains of ZEKE were later salvaged, with Strangelove remarking that the AI has a backup copy. Strangelove and Huey also began to have a better understanding of each other.

A few hours after the destruction of ZEKE, Kaz admitted learning of Paz's real identity and purpose well beforehand and that "Cipher" was Major Zero, who perpetrated the whole plot and indirectly triggered MSF's expansion. Although Snake was angry at him, Kaz explained that the MSF set a new trend in military operations with their actions in Costa Rica, and predicted that the end of the Cold War would give rise to regional conflicts where the MSF could thrive. Since the MSF's battle capabilities disrupted the global military balance of power, Snake warned that certain forces would definitely try to take them down, hence their need to continue operating outside of society.

In a later address over a loudspeaker, Snake told his troops that their group would serve under anyone regardless of nations and ideologies, and they would soon build a nation they could call their own, called Outer Heaven.

Aftermath
Having failed at getting Snake to rejoin Cipher as well as not gaining total control of ZEKE and MSF, the organisation devised a new plan to destroy MSF and Snake out of revenge. Snake and Kaz meanwhile would later discover that Paz survived the battle and is captured by Cipher via XOF (who at the time was aligned with them) at Camp Omega in Cuba due to suspicions that she had been compromised, and planned to rescue her as she was their only viable link to Cipher.

Behind the scenes
During the meeting with both Huey Emmerich and Cecile Caminandes, Big Boss, in an attempt to cover up his reasons for being in Costa Rica, mentioned that he was searching for a particular animal (the Morphos Butterfly and the Quetzal, respectively) for the Washington Treaty. This referred to the CITES Treaty relating to the endangered status of animals.