Medium Fusion Destructive Device

The Medium Fusion Destructive Device, or MFDD, is a tactical nuclear weapon with a 63 terajoule output, used by the United Nations Space Command.

Trivia

 * The MFDD is first seen in the "Deliver Hope" trailer for Halo: Reach. Due to its size and apparent blast radius, it may actually be the Fury Tactical Nuclear Weapon.