Task: Question Generation
Input (English):  In 1996, as part of a new military training program, a group of orphaned infants are selected at birth and raised as highly disciplined soldiers with no understanding of anything but military routine. They are trained to be ruthless obedient killers, and all those considered to be physically or mentally unworthy are executed. The survivors are turned into impassive dedicated fighting machines with no exposure to or understanding of the outside world.
In 2035, at the age of 39, Sgt. Todd 3465 is a hardened veteran and the best soldier of the original 1996 infants, but his unit is challenged for replacement by a superior unit. Colonel Mekum, leader of the original project, introduces a new group of genetically engineered soldiers, designed with superior physical attributes and a complete lack of emotion, except complete aggression.
Captain Church, the commander of Todd's unit, insists on testing the new soldiers' abilities against his proven older ones. A new soldier, Caine 607, easily defeats three of the original soldiers, but Todd gouges out Caine's eye before he seemingly dies when he falls from a great height; the body of a dead soldier actually cushioned his fall, and he is simply stunned and knocked unconscious. Mekum orders their bodies disposed of like garbage, declaring them obsolete, while the remaining older soldiers are demoted to menial unarmed support roles.
Dumped on Arcadia 234, a waste disposal planet, Todd limps toward a colony whose residents crash-landed there years earlier; as they were believed dead, no rescue missions have been attempted. Todd is sheltered by Mace and his wife Sandra. Though they try to make him welcome, Todd has difficulty adapting to the community due to his extremely rigid impassive conditioning and their conflict-free lives. Todd develops a silent rapport with their mute son, Nathan, who had been traumatized by a snakebite as an infant, and watches upon the happy loving family with yearning in his eyes. When the child silently looks to him for a defense against a coiled snake, Todd refuses, demanding that Nathan face it down and strike back to protect himself. Nathan's parents intervene and disapprove of the lesson, unsure of how to deal with the silent soldier. Todd becomes disoriented by exposure to peaceful civilian life and soon begins to experience flashbacks from his time killing civilians and battling other soldiers. To make matters worse, he mistakes one of the colonists for an enemy when the fellow surprises him, nearly killing him. Fearful, the colonists expel Todd from the community. Apparently rejected by every society he has known, the military and the refugee civilians, Todd shows strong emotion for the first time after being expelled. Overcome by loss, he quietly cries. A short time later, Mace and Sandra are almost bitten by a snake while they sleep, but they are saved by Nathan's use of Todd's aggressive defensive technique to protect them. Now understanding the value of Todd's lesson, they seek him to reintegrate him into the community, regardless of the opposition of the others who fear him.
The new genetically engineered soldiers arrive on the garbage planet, and, since the world is listed as uninhabited, Colonel Mekum decides to use the colonists' community as the target in a training exercise. Just after Mace finds Todd, apologizes and invites him back, the soldiers spot Mace and kill him. Though out-manned and outgunned, Todd's years of battle experience and superior knowledge of the planet allow him to return to the colony and kill the advance squad. Nervous that an unknown enemy force may be confronting them, Colonel Mekum orders the soldiers to withdraw and return with heavy artillery. Using guerrilla tactics, Todd outmaneuvers and defeats all of the remaining soldiers, including Caine 607, whom he defeats in vicious hand-to-hand combat by clever tactics rather than mere physical prowess.
Panicking, Mekum orders the transport ship's crew, composed of Todd's old squad, to set up and activate a portable nuclear device powerful enough to destroy the planet. He then orders the ship to lift off, leaving the squad behind. When Captain Church objects, Mekum shoots him in cold blood. Before they can take off as planned, Todd appears, and his old comrades silently side with him over the army that has discarded them. They take over the ship, leaving Mekum and his supportive aides on the planet while they evacuate the remaining colonists. In an attempt to disarm the nuclear device, Mekum accidentally sets it off, killing him and his aides. Todd pilots the ship from Arcadia just ahead of the shockwave and sets course for the Trinity Moons, the colonists' original destination. When Nathan enters the control room and reaches for Todd, he then picks up Nathan and points to their new destination, while looking out upon the galaxy.
Output (English): Why is the old unit replaced?