Hypersonic glide vehicle (HGV) is a type of warhead for ballistic missile that can maneuver and glide at hypersonic speed. It is used on ballistic missiles to significantly change their trajectories. Conventional ballistic missiles follow a predictable ballistic trajectory and are vulnerable to interception by the latest anti-ballistic missile (ABM) systems. HGV makes them unpredictable, allowing them to evade air defenses. Hypersonic glide vehicles are currently subject of an arm race.