Defensive Kinetic Kill Missile is a defensive weapon against incoming offensive missiles in ship to ship combat and can also be used against enemy fighters. Defensive missiles are smaller missiles (about 1/3 of a kilogram), which move slower than offensive missiles (60 to 70 PSL), but with twice the acceleration.
Kinetic warheads do not carry an explosive payload, but rather rely on the fact that kinetic energy equals one-half mass times velocity-squared (ie, .33 Kg x 70% of 300,000 kilometers per second). Thus when defensive missiles impact with a ship, they cause incredible damage, with many megatons of energy. This is usually enough to destroy any incoming missile or fighter.