A three-body interception scenario is considered where an aircraft launches a defending missile as a counter weapon against an incoming attacking missile. Line of sight guidance is investigated as a prospective strategy for the defender missile with the aircraft being the moving launch platform. Kinematic results are derived showing defender-attacker interception for all attack geometries and attacker maneuvers. The speed and maximum terminal acceleration requirements are shown to be considerably lower as compared to a proportional navigation guided defender missile. It is also shown that the attacker pays maximum penalty for an evasive maneuver from defender if the defender uses line of sight guidance. A cooperative guidance law is proposed for the aircraft to maximize the attacker to defender lateral acceleration ratio. Simulations are carried out for various attack geometries with and without the cooperative strategy, showing better relative control effort performance for the former.