Template:Weapon The Harpoon nuclear missile was to be a United Nations Space Command starship-mounted thermonuclear weapon. It is mentioned in a piece of concept art for the UNSC corvette Andraste that Isaac Hannaford designed for Halo 3, though it was not featured in the game.[1]
What appear to be Harpoon missile tubes appear in Halo: Reach on the Paris-class heavy frigate, UNSC Pillar of Autumn and Anchor 9, though they never function in-game.
It shares its name with a modern-day anti-ship missile.
Gallery
Under-construction frigates in Long Night of Solace show the tubes extending below deck.
Sources